Ex  Libris 
C.  K.  OGDEN 


^ 


^■' 


AUTOMATIC  SCREW  MACHINES  AND  THEIR  TOOLS 


AUTOMATIC  SCREW  MACHINES 
AND   THEIR   TOOLS 


BY 

C.   L.   GOODRICH 

Expert  on  Screw  Machine  Tools  and  Department  Foreman 

of  Pratt  and  Whilney  Company;  Author  of 

"Accurate  Tool  Work" 


AND 

F.   A.   STANLEY 

Associate  Editor  American  Machinist;  Author  of  " American 

Machinists'  Handbook,"  "Hill  Kink  Books"  and 

"Accurate  Tool  Work" 


1909 
HILL    PUBLISHING    COMPANY 

505    PEARL   STREET,  NEW   YORK 

6  BOUVERIE  STREET,  LONDON',  E.G. 

Amirican  Machinist  — Pourr  and  The  Engineer —The  Engineering  and  Mining  Journal 


Copyright,  1909,  by  The  Hill  Publishing  Company 


Hill  Publishing  Company,  New  To>k,  U.S.A. 


PREFACE 

In  the  preparation  of  this  book  on  automatic  screw  machines  and 
their  tool  eciuipment,  we  have  endeavored  to  embody  material  which  will 
constitute  a  comprehensive  treatise  for  tool  designers,  toolmakers,  and 
machine  op(M"ators. 

The  subject-matter  of  the  book  divides  naturally  into  two  sections, 
one  devoted  to  various  types  of  machines  and  their  construction,  general 
tool  equipments,  methods  of  camming,  etc.;  the  other  dealing  with  tools 
in  detail,  and  containing  specific  information  on  making  and  using  these 
tools,  the  speeds  and  feeds  at  which  they  should  be  operated,  and  other 
particulars  which  it  is  hoped  may  be  of  service  to  mechanics  connected 
with  screw  machine  work.  The  chapters  on  camming  and  on  different 
types  of  cutting  tools  were  prepared  originally  for  publication  in  the 
columns  of  the  Aiiierican  Machi7iist;  they  are  here  arranged  in  some- 
what more  convenient  form  of  reference. 

It  will  be  noted  that  in  Section  I  a  number  of  machines  are  included 
which,  strictly  speaking,  are  of  the  chucking  machine  type  and  "semi- 
automatic "'  in  their  operation,  the  chucking  of  the  work  being  accom- 
plished by  hand.  Aside  from  this  feature,  they  are,  broadly  considered, 
similar  in  principle  to  the  full  automatic  machines,  although  their  capacity 
antl  the  method  of  holding  the  material  adapt  them  to  the  machining  of 
a  heavier  or  otherwise  different  class  of  work  from  that  usually  produced 
on  "automatics"  working  entirely  from  bar  stock  or  on  castings  and 
forgings  fed  to  the  chuck  by  means  of  magazines. 

We  recognize  the  fact  that  the  name  "automatic  screw  machine" 
is  hardly  broad  enough  for  the  designation  of  a  machine  which  can  pro- 
duce from  the  bar,  from  castings  or  from  forgings,  almost  any  symmetrical 
piece  that  may  fall  within  the  capacity  of  the  chuck  and  turret  traverse. 
However,  the  purpose  for  which  this  type  of  machine  was  originally  con- 
ceived, naturally  determined  its  title,  and,  although  to-day  the  making 
of  screws  is  but  a  small  part  of  the  work  it  accomplishes,  it  is  still  gen- 
erally known  by  its  original  name.  A  few  makers,  especially  of  the  medium 
and  larger  sizes  of  machines,  refer  to  them  as  automatic  "turret  lathes" 
and  automatic  "turret  machines,"  and  in  the  chapter  headings  we  have 
followed  the  respective  manufacturers'  preferences  in  the  matter. 

The  Authors. 


20001 51 


CONTEXTS 


I 

II 
III 

IV 
V 

VI 

VII 

VIII 

IX 

X 

XI 

XII 

XIII 

XIV 

XV 

X\I 

XVII 

XVIII 


SECTION   I 

PAGE 

The  Pratt  &  Whitney  Automatic  Screw  Machine 3 

Camming  the  Pratt  it  Whitney  Automatic  Screw  Machine    .      .  12 

The   Brown  it  Shari'e  Automatic  Screw  Machine 37 

Laying  Out  the  Brown  it  Sharps  Screw   Machine  Cams       .      .  52 
The  Brown  it  Sharpe  Automatic  Screw  Machine  with  Constant- 
Speed  Drive 64 

The  Cleveland  Automatic  Turret  Machine  and  Its  Cam  Adjust- 
ments          67 

The  Gridley  Automatic  Turret  Lathe 78 

The  Alfred  Herbert  Automatic  Screw  Machine 89 

The  New  Spencer  Double-Turret  Automatic  Screw  Machine     .  91 

The  Cleveland  Double-Spindle  Plain  Automatic  Machine     .      .  93 

The  Acme  Multiple-Spindle  Automatic  Screw  Machine     ...  95 

The    rNIVKRSAL    MCLTII'LH-SPINDLE    AUTOMATIC    ScREW    MaCHI.NE           .  114 

The  Cridley  Multiple-Spindle  Automatic  Turret  Lathe        .      .  119 

The   Cleveland  Auto.matic   M.vchine  with   Magazine  Attachment  126 

The  Alfred  Herbert  Macjazine  .\utomatic  Screw  .Machine     .      .  128 

The  Potter  <t  John.ston  Automatic  Chucking  and  Turning  Machine  135 

The  CJridley  Semi-.\utomatic  Piston  Ring  M.vchine       ....  144 

The  Prentice  Multiple-Spindle  Automatic  Turret  Machine  147 


SECTION    II 

XI.X  Points  in  Setting  Up  and  Operating  .\utomatic  Screw  Mac 

.\.\  Speeds  and  Feeds  for  Screw  Machine  Work 

N.\I  Spring  Collets  and  Feed  Chucks 

XXII  Box  Tools  and  Other  External  Cutting  .\ppliances    . 

XXIII  Drills,  Counterbores  and  Other  Internal  Cutting  Tools 

XXIV  Screw  Machine  T.\ps  and  Dies 

XX\'  Forming  Tools  and  Methods  of  Makinc;  Them 

XXVI  Nurling  Tools  and  Their  .\pplic.vtions 

XXVII  Why  Chips  Cling  to  Screw  Machine  Tools     .... 


1.39 
1(12 
171 
17.) 
187 
195 
210 
230 
234 


SECTION   I 

TYPES    OF   MACHINES 
METHODS  OF   CAMMING  AND   TOOL   EQUIPMENTS 


CHAPTER   I 

The  Pratt  &  Whitney  Automatic  Screw  Machine 

The  automatic  screw  machine  built  by  the  Pratt  &  Whitney  Company, 
Hartford,  Conn.,  is  of  the  vertical  turret  type,  with  cam  drums  carried 
upon  opposite  ends  of  a  longitudinal  shaft  ff)r  operating  the  turret  and 


4  THE   PRATT  &   WHITNEY  AUTOMATIC   SCREW   MACHINE 

the  chucking  and  feeding  mechanism.  This  machine  is  illustrated  as  a 
whole  by  the  half-tone  engraving,  Fig.  1;  the  line  drawings  Figs.  2  to  5 
showing  the  principal  features  of  construction. 

ARRANGEMENT    OF    CAM    DRUMS    AND    DISKS 

The  drum  seen  in  Fig.  1  near  the  right-hand  end  of  the  main  shaft 
carries  a  series  of  plain  strap  cams  arranged  obliquely  for  moving  the 
turret  slide  to  and  fro;  the  drum  at  the  left  end  is  fitted  with  cams  of 
the  same  general  character  for  opening  and  closing  the  chuck  and  feed- 
ing the  stock  through  the  spindle.  The  disk  located  at  about  the  middle 
of  the  length  of  the  shaft  has  on  its  right  face  ordinarily  a  pair  of  flat  cams 
which  operate  a  vertical  lever  at  the  front  of  the  cross  slide  and  move 
the  slide  toward  the  rear;  the  opposite  face  of  the  disk  is  provided  with 
similar  cams  which  act  upon  a  corresponding  lever  at  the  rear  of  the  cross 
slide  to  move  the  slide  toward  the  front  of  the  machine.  The  smaller 
disk  immediately  under  the  head  carries  a  series  of  dogs  adjustable  about 
the  disk  periphery  and  adapted  to  control  the  shifter  lever  which  moves 
the  open  and  cross  belts  on  and  off  the  tight  and  loose  pulleys  on  the 
spindle.  Dogs  of  similar  form  are  carried  on  the  spider  disk  at  the 
extreme  right-hand  end  of  the  machine,  for  controlling  the  fast  and 
slow  feed-driving  mechanism  which  rotates  the  cam-drum  shaft  through 
the  medium  of  worm  and  worm  wheel,  both  of  which  are  plainly  visible  in 
the  half-tone. 

THE    SPINDLE    AND    CHUCK    MECHANISM 

As  will  be  seen  upon  examination  of  Fig.  2,  the  spindle  carries  a  pair 
of  loose  pulleys  for  the  forward  and  reversing  belts,  and  between  them 
is  a  third  pulley  secured  to  the  spindle  and  driving  it  in  either  direction 
according  to  which  belt  is  operating  on  it  at  the  time.  The  spring  collet 
for  holding  the  bar  stock  and  the  feed  tube  for  moving  the  bar  forward 
when  the  chuck  is  opened  are  plainly  shown  in  the  sectional  drawing,  as 
is  also  the  mechanism  at  the  rear  of  the  spindle  for  operating  the  chuck 
and  feed. 

In  this  illustration,  A  is  a  sliding  block  that  moves  feed  tube  B  to 
and  fro,  and  C  another  sliding  block  that  closes  the  chuck  through  the 
medium  of  sliding  cone  D,  pivoted  fingers  E,  and  tube  F  which  extends 
through  the  spindle  G.  Both  sliding  blocks  .4.  and  C  are  operated  by 
cams  on  the  "chucking"  drum  directly  beneath,  and  these  cams,  here 
shown  in  outline,  will  be  referred  to  later.  It  may  be  stated  here,  how- 
ever, that  the  distance  the  stock  is  fed  when  the  chuck  is  opened  is 
determined  to  within  close  limits  by  the  distance  the  feed  tube  is  drawn 
to  the  rear  by  its  cam  while  the  chuck  is  closed.  p]xact  feeding  to  length 
is  of  course  assured  by  using  a  stock-stop  in  the  turret. 

The  "feed  fingers"  screwed  into  the  front  end  of  the  feed  tube  B 


THE  SPINDLE   AND   CHUCK  MECHANISM 


6 


THE    PRATT   &    WHITNEY   AUTOMATIC   SCREW   MACHINE 


maintain  a  constant  spring  grip  on  the  bar  of  stock  and  are  ready  to  carry 
the  bar  forward  the  moment  the  chuck  is  opened.  The  latter  has  suffi- 
cient expanding  tendency  due  to  the  method  of  spring  tempering  to 
release  its  grip  on  the  stock  the  instant  the  operating  block  C  is  slid 
forward  by  its  cam  to  withdraw  cone  D  from  between  fingers  E.  The 
chuck  may  be  operated  by  hand  at  any  time  in  setting  up  by  means  of 
a  crank-actuated  pinion  and  rack  connected  with  block  C.  The  arrange- 
ment of  the  cams  for  the  chuck  and  stock  feeding  mechanism  as  well  as 
for  operating  the  turret  slide  are  fully  described  in  the  next  chapter  of 
this  book  under  the  general  heading  of  camming. 


THE    TURRET    SLIDE    AND    TURRET 


The  turret  and  its  slide  are  shown  in  Fig.  3.  The  slide  is  reciprocated 
by  the  roll  underside  which  contacts  with  the  cams  on  the  drum  below. 
The  turret  is  indexed  step  by  step  at  each  return  of  the  slide  by  the  four- 


Turret  Locking 

ilechanism 


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Fig.  3.  — Construction  of  Turret  Slide  and  Turret 

toothed  ratchet  wheel  a,  which  is  secured  to  the  bottom  of  the  turret 
and  as  it  is  carried  to  the  right  comes  into  engagement  with  the  end  of 
pawl  b,  whose  rear  end  is  pivoted  in  the  turret-slide  block  and  whose 
forwai'd  end  is  kept  constantly  against  the  periphery  of  the  toothed 
ratchet  by  spring  plunger  c. 


THE  CROSS   SLIDE  7 

Immediately  prior  to  the  ratchet  coming  into  contact  with  the  for- 
ward end  of  the  pawl,  the  locking  bolt  d  is  withdrawn  from  the  notch  in 
the  indexing  ring  e  by  its  pin  /  coming  in  contact  with  the  inclined  surface 
at  the  forward  end  of  wedge  g  pivoted  at  the  rear  of  the  turret-slide  block. 
As  shown  in  the  general  plan,  and  in  the  sectional  view  with  the  locking 
bolt  guide  cover  removed,  the  bolt  is  withdrawn  from  the  index  ring. 
The  turret  is  shown  ready  to  start  rotating  and  upon  a  slight  further 
movement  to  the  rear  the  rotary  action  commences  and  the  locking  bolt 
clearing  the  heel  of  the  wedge  by  which  it  is  withdrawn,  is  forced  by  its 
spring  against  the  index  ring  and  drops  into  the  next  notch  when  that 
notch  is  brought  opposite  the  bolt  end  upon  the  completion  of  the 
quarter  turn  of  the  turret. 


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5 


a 


Fi<j.  4  —  The  Cross  Slide  and  its  Operatinji  Levers 

The  method  of  gibbing  the  locking  bolt  is  shown  in  the  drawing.  The 
bolt  itself,  as  will  be  noticed,  has  one  radial  side  sliding  against  a  cori-c- 
sponiling  side  of  the  notch  in  the  index  ring  and  locates  the  turret  accu- 
rately, while  the  wear  due  to  the  thrust  is  taken  on  the  relatively 
unimportant  bevelled  side  of  the  bolt. 


THE    CROSS    SLIDE 


The  cross  slide,  shown  in  Fig.  4,  is  adapted  to  carry  front   and  rear 
blocks  for  forming  and  cut-off  tools  and  is  operated  by   the  two  levers 


8  THE   PRATr   &    WHITNEY   AUTOMATIC   SCREW   MACHINE 

and  the  cam  disk  already  mentioned.  Both  levers  carry  screws  in  their 
upper  ends  which  may  be  adjusted  to  feed  the  cross  slide  to  the  desired 
point  in  either  direction.  The  cam  disk  is  shown  blank  in  this  engrav- 
ing, but  when  fitted  up  for  operation  it  carries  cams  on  either  side  like 
those  shown  in  place  on  the  disk  in  Fig.  1. 

THE    FEED    DRIVE 

Fig.  5  illustrates  the  fast  and  slow  feed-driving  motion  which  actu- 
ates the  cam-drum  shaft,  providing  a  rapid  movement  of  the  cams  and 
tools  while  the  latter  are  not  cutting,  and  a  slow  motion  during  actual 
cutting  operations.  The  slow  motion  is  obtained  through  the  planetary 
gears  H,  I,  J,  K.  Gears  H  and  /  are  differential  drivers  mounted  on  a 
stud  secured  in  the  web  of  the  driving  pulley  as  indicated.  Gear  K  is 
keyed  to  the  worm  shaft,  and  J  to  ratchet  L,  which  is  locked  by  pawl 
M  during  the  slow  motion,  the  clutch  A^  when  thrown  into  action  giving 
the  quick  rate  of  speed  to  the  driving  worm  which  is  then  driven  direct 
from  the  pulley  instead  of  through  the  differential  gears  H,  I,  J,  K.  As 
previously  stated,  dogs  carried  on  the  disk  at  the  right-hand  end  of  the 
drum  shaft  control  the  mechanism,  causing  the  clutch  to  be  engaged  and 
disengaged  at  the  proper  intervals.  The  clutch  is  normally  held  out  of 
engagement  by  latch  0,  which  engages  with  a  collar  on  spring  shaft  P. 
When  arm  Q  is  actuated  by  one  of  the  dogs  on  the  controlling  disk,  wedge 
R  causes  latch  0  to  lift  and  release  the  rod  P,  which  is  then  carried  by 
its  spring  to  the  right,  throwing  in  the  clutch.  The  next  dog  on  the  disk 
causes  the  spring-actuated  rod  to  be  drawn  back,  releasing  the  clutch  and 
allowing  the  latch  0  to  drop  into  its  original  position,  and  hold  the  clutch 
open. 

A  common  ratio  of  fast  to  slow  motion  is  24  to  1  on  several  sizes  of 
this  type  of  machine  (that  is,  in  driving  through  the  planetary  gearing 
Fig.  5  the  pulley  makes  24  turns  to  1  of  the  worm  shaft) ,  but  several 
other  ratios  are  provided  for  by  means  of  gears,  which  may  be  changed 
in  the  planetary  drive.  These  ratios,  together  with  the  series  of  feed- 
driving  pulleys  for  the  countershaft,  and  the  drums  for  driving  the  spindle 
speeds,  give  a  wide  range  of  ratios  between  drum  shaft  and  spindle 
speeds,  and  by  varying  the  cam  angles  a  broad  range  of  feeds  for  the 
tools  varying  by  very  small  increments  are  obtainable.  The  method  of 
camming  this  type  of  machine  is  described  fully  in  the  next  chapter. 

Various  classes  of  tools  for  this  machine  are  illustrated  in  different 
chapters  in  Section  II. 

COUNTERSHAFT    ARRANGEMENT 

The  countershaft  and  method  of  belting  to  the  machine  are  illus- 
trated in  Fig.  6,  which  shows  also  the  scheme  of  setting  the  machine  at 


ARRANGEMENT   OF    FEED    DRIVE 


10 


THE   PRATT   &   WHITxNEY   AUTOMATIC   SCREW    MACHINE 


an  angle  with  the  center  hne  of  countershaft.  This  anguLar  setting 
which  is  common  to  screw  machine  practice  allows  the  bar  of  stock  to  pass 
behind  the  machines  set  immediately  to  the  left,  thus  permitting  all 
the  machines  in  a  row  to  be  placed  very  closely  together.  As  shown,  the 
end  of  the  machine  is  swung  out  of  line  until  the  pulley  for  driving  the 
worm  mechanism  for  operating  the  cam  drum  shaft  is  in  proper  location 


Fig.  6.  —  Countershaft  and  Drive  for  Pratt   &  Whitney  Automatic  Screw  Machine 


relative  to  the  feed  pulley  on  the  countershaft,  the  drive  from  that  pulley 
to  the  feed  pulley  on  the  machine  being  by  means  of  a  quarter  turn  belt. 
The  countershaft  is  represented  with  two  sizes  of  pulleys  for  driving  the 
head  spindle,  and  with  a  pulley  to  the  left  for  operating  the  geared  oil 
pump.  The  speed  rates  derived  for  the  spindle  by  the  driving  method 
illustrated  are  discussed  in  the  chapter  following  on  camming. 


rilTTK    STZKS    AXD    LKXCTII    OF    IKED  11 

CHUCK    SIZES    AXD    LENGTH    OF    FEED 

The  No.  0  machine  of  this  type  takes  bar  stock  up  to  ^%  inch,  and 
turns  lengths  up  to  1/^  inch.  The  No.  1  machine  takes  stock  up  to  ^ 
inch  and  turns  up  to  2^  inches  in  length.  The  No.  2  machine  handles 
stock  up  to  if-incli  diameter  and  turns  lengths  up  to  2J  inches.  The 
"oversize"  maciiines  "lA"  and  "2A"  have  increased  chuck  capacities 
taking  respectively  f  and  1  inch  stock. 


CHAPTER   II 

Camming  the  Pratt  &  Whitney  Automatic  Screw  Machine 

A  DIAGRAM  of  the  Pratt  &  Whitney  automatic  screw  machine  with 
a  set  of  cams  in  place  is  given  in  Fig.  7,  *S  being  the  chucking  drum;  T 
the  turret-slide  drum;  U  the  disk  for  the  cross-slide  cams;  V  the  disk 
which  carries  the  dogs  for  controlling  the  feed  motion;  W  the  disk  whose 
dogs  operate  the  lever  for  shifting  the  spindle-driving  belts.  Fig.  8  shows 
the  development  of  the  two  cam  drums  with  cams  arranged  for  operating 
on  a  piece  like  Fig.  9.  It  will  be  seen  that  the  turret  cams  fill  the 
periphery  of  the  drum,  which  is  a  desirable  feature  in  the  majority  of  cases 
as  waste  of  time  is  then  avoided. 

CAMMING  the  CHUCKING  DRUM 

As  it  is  essential  before  camming  the  turret-slide  drum  to  know  what 
space  will  be  required  in  unlocking  and  locking  the  chuck  and  feeding 
out  the  stock,  the  chucking  drum  S,  Fig.  7,  is  first  cammed  without  the 
necessity  of  a  layout  on  paper,  as  is  required  in  the  case  of  the  turret 
drum.  It  is  assumed  that  the  piece  of  work  has  just  been  severed  from 
the  bar,  the  chuck  being  locked  firmly.  The  chuck  is  now  unlocked  as 
a  starting  point,  and  the  unlocking  cam  a  put  on,  the  angle  of  this  cam 
being  about  25  degrees  with  the  edge  of  the  drum.  The  cam  length 
must  be  sufficient  to  move  chuck  roll  h  far  enough  to  release  the  spring 
chuck  completely  from  the  work.  As  soon  as  the  chuck  opens,  the  stock 
is  ready  to  be  fed  forward,  this  movement  being  accomplished  by  cam  c, 
which  should  be  so  put  on  as  to  contact  with  feed  roll  d  immediately  upon 
the  unlocking  of  the  chuck.  An  angle  of  50  degrees  is  the  usual  slope 
for  the  stock  feed  cam;  the  length  is  obviously  made  to  give  a  throw  equal 
to  or  slightly  in  excess  of  the  longest  piece  that  the  machine  will  produce. 
The  chuck-locking  cam  e  is  next  to  be  considered,  and  this  is  so  located 
as  to  contact  with  chuck  roll  6,  and  start  closing  the  chuck  the  instant  the 
feed  cam  c  has  carried  the  feed  roll  d  to  the  extreme  forward  position. 
Where  the  work  is  of  a  light  nature  and  the  chuck  easily  gripped  on  the 
stock,  the  angle  of  the  chuck-closing  cam  e  may  be  made  the  same  as  that 
of  the  unlocking  cam  a,  namely  25  degrees;  for  work  of  a  heavier  character 
20  degrees  is  a  more  suitable  angle.  In  locating  the  feed  cam  c  the  feed 
plunger  should  be   pushed  forward   into  the  spindle  until  the  grooved 

12 


CAMMING  THE  CHUCKING   DliUM 


13 


a  ^ 

3  a 

o  a 

a  o 
S  J 


^71 

h//; 

3 

•3 
< 

s 

^'  t 

Space  required  for 
unlocking  Chuck  Feeding 
Stock  and  Locking  Chuck. 


Space  required  lor 
Cutting  OIT. 


Cam  Arranfiemont 


14       CAMMING  THE  PRATT  &  WHITNEY  AUTOMATIC  SCREW  MACHINE 

collar  /  is  against  the  nurled  collar  g  at  the  rear  of  the  chucking  finger 
ring,  which  limits  the  forward  movement  of  the  feed  tube  and  its  roll  d; 
it  is  apparent  that  this  determines  the  position  of  the  high  point  of  the 
feed  cam,  though  the  left-hand  end  of  that  cam  may  be  extended  to 
the  edge  of  the  drum  or  beyond,  if  desirable,  as  in  the  case  of  extra  long 
feeds. 

The  feed  "draw  back"  cam  //  is  the  last  one  to  go  on  the  drum;  its 
function  is  to  draw  the  feed  tube  to  the  rear,  bringing  the  roll  d  into  posi- 
tion to  be  pushed  forward  again  by  the  feed  cam  c  as  soon  as  the  chuck 
again  opens.  The  "draw  back"  cam  is  pivoted  as  indicated,  and  may 
be  adjusted  to  give  any  desired  length  of  feed  within  the  capacity  of  the 
machine.  In  locating  this  cam  its  pivoted  end  must  be  so  positioned 
as  not  to  strike  the  chuck-operating  roll  h. 

As  already  stated,  the  camming  of  the  chucking  drum  may  be  done 
satisfactorily  without  a  layout  on  the  drawing  board,  though  where 
several  machines  are  being  cammed  such  a  drawing  may  prove  of  consid- 
erable service. 

THE    TURRET-SLIDE    DRUM 

In  camming  the  turret-slide  drum  a  full-size  drawing  should  always 
be  made,  the  drum  periphery  being  first  laid  out  on  paper  as  a  rectangle, 
whose  length  and  breadth  represent  respectively  the  circumference  and 
width  of  the  drum.  A  development  of  a  turret-slide  drum  surface  is 
seen  in  Fig.  8,  with  three  locating  lines,  i,  k,  I  for  the  series  of  cams.  The 
position  of  these  lines  may  be  obtained  as  follows:  A  set  of  tools  being 
placed  properly  in  the  turret,  the  latter  is  pushed  forward  as  far  as  re- 
quired to  bring  the  tools  in  the  right  position  relatively  to  the  work, 
after  which  a  scriber  is  placed  at  the  right  side  of  the  roll  m,  which  oper- 
ates the  slide,  and  a  line  i  is  scribed  on  the  drum  to  represent  the  extreme 
forward  position  of  the  turret,  hence  no  cams  advancing  the  turret 
toward  the  chuck  can  project  beyond  this  line.  Next  the  turret  slide 
is  moved  back  to  the  point  where  the  turret  commences  to  index,  and  a 
line  k  is  scribed  on  the  drum  |  inch  from  the  left  side  of  the  roll  m,  after 
which  the  slide  is  drawn  clear  back  to  the  right  as  far  as  possible,  this 
movement  completing  the  indexing  and  locking  of  the  turret,  and  a  third 
line,  I,  is  then  scribed  at  the  left  side  of  roll  m.  The  reason  for  scribing 
line  k  (which  locates  the  leading  ends  of  the  index  cams)  one-quarter 
inch  to  the  left  of  the  point  where  indexing  really  commences,  is  that  we 
then  insure  the  easy  index  cams  coming  into  contact  with  the  turret- 
slide  roll  slightly  before  the  slide  actually  reaches  the  indexing  point. 

We  can  now  draw  the  three  lines  scribed  on  the  drum  on  the  full- 
size  layout  on  the  drawing  board,  as  shown  in  the  development,  Fig.  8, 
and  thus  have  the  correct  distance  between  the  lines  i  I  and  k  I.  In  this 
case  we  will  call  the  former  distance  2\  inches,  and  the  latter  1|  inches, 


FEED   CALCULATIONS 


15 


and  may  now  proceed  wth  the  figuring  of  the  cams  for  producing  the 
piece,  Fig.  9. 


Fig.  9. 


The  Work 


FEED    CALCULATION'S 

We  will  assume  a  speed  of  2o0  revolutions  per  minute  as  suitable  for 
the  work,  and  use  a  starting  or  centering-and-facing  tool  in  the  first  turret 
hole,  a  iV  inch  twist  drill  in  the  second  hole,  a  roughing  counterbore  in 
the  third  hole,  and  a  finisliing  counterbore  in  the  fourth  or  last  hole.  In 
atldition  to  the  length  of  cutting  feed  required  for  each  tool  we  will  add 
j-  inch  in  each  case  for  safety,  and  to  allow  for  slight  modifications  in  the 
character  of  the  piece,  thus  making  it  possible  for  the  slow  feed  to  start 
into  action  as  each  tool  reaches  a  point  |  inch  away  from  the  actual  start- 
ing point  of  its  cut.  A  schedule  of  the  tool  feeds  may  now  be  laid  out  as 
in  Table  1. 

First  hole.        Starting  tool,             0.004"  feed  l"  deep  +  i"  allowance  =  ^'' 

Second  hole.     yV  t"ist  drill,             0.005"  feed  U"  deep  +  i"  allowance  =  {'f 

Third  hole.       Roufih  counterbore.  0.010"  feed   l"  deep  +  I"  allowance  =  |" 

Fourth  hole.     Finish  counterbore,  0.01.5"  feed  |i"  deep  +  }"  allowance  =  ^f 

Finish  counterbore,  0.00.")"  feed  3V"  for  bottom  of  cut        =  5^" 

Combined  length  of  feed  of  all  tools                                  =  o^iy 

Table  I.  — Tool  Feeds  for  Work  Shown  in  Fiji.  9 

For  carrying  the  turret  forward  to  the  point  of  cutting  and  for  bring- 
ing it  back  to  the  point  where  indexing  commences,  cam  angles  of  50 
degrees  with  the  edge  of  the  drum  are  generally  u.sed.  Sometimes  this 
angle  is  exceeded  by  a  few  degrees.  55  degrees  being  about  the  practical 
maximum  limit,  while  it  is  very  seldom  necessary  to  drop  below  50  degrees. 
The  travel  of  the  turret  slide  while  indexing  (from  k  to  /,  Fig.  8)  should  not 
generally  be  much  greater  than  20  feet  per  minute,  this  depending,  how- 
ever, upon  the  size  of  machine  and  tools  used.  This  rate  of  travel  with 
the  work  revolving,  as  stated  above,  at  250  turns  per  minute,  would  be 
equivalent  to  240  inches  for  250  turns  of  the  spindle  or  0.96  inch  per 
revolution.  While  the  indexing  is  done  with  the  fast  speed  of  the  cam- 
drum  shaft,  it  is  desirable  in  the  cases  of  all  turret-slide  movements  for 
which  cams  have  to  be  figured  to  state  the  feed  per  turn  of  spindle  at  its 
equivalent  at  slow  cam-shaft  speed.  With  a  feed  motion  having  a  ratio 
of  24  to  1  this  means  that  the  indexing  movement  of  0.96  inch  per  turn 


16       CAMMING  THE  PRATT  A:   W  HTrXEY  AUTOMATIC  SCREW  MACHINE 

when  expressed  at  the  slow  cam-shaft  rate  would  be  0.96  divided  by  24  = 
0.04  inch  per  revolution. 

HOW    THE    DRI'M    SURFACE    IS    UTILIZED 

Before  figuring  the  angles  for  the  cutting  and  indexing  cams  we  can 
simplify  matters  by  taking  from  the  total  circumference  of  the  drum, 
which  measures,  say,  48  inches,  the  amount  of  space  as  measured  around 
the  drum  periphery  utilized  by  the  50-degree  cams,  the  eight  roll  spaces, 
and  eight  |-inch  flats  formed  by  dressing  off  the  forward  ends  of  the 
four  cutting  cams  and  the  rear  ends  of  the  four  indexing  cams  to  obviate 
wear  of  the  cam  corners.  The  distance  i  to  /,  Fig.  8,  which  as  already 
stated  is  2\  inches,  is  temporarily  taken,  for  purposes  of  calculation,  as 
representing  the  forward  and  backward  travel  of  the  turret  slide.  Ac- 
tually, of  course,  the  travel  would  be  equal  to  the  distance  between  the 
centers  of  roll  m  in  the  extreme  forward  and  backward  positions.  How- 
ever, it  is  more  convenient  and  in  no  way  affects  the  result  to  assume 
distance  i  to  I  as  defining  the  true  length  of  travel. 

That  is,  we  can  assume  for  the  moment  that  the  roll  is  of  infinitely 
small  diameter,  its  travel  then  being  simply  from  line  i  to  /.  Now  if  we 
increase  the  roll  diameter  to  1\  inches  we  merely  extend  the  outer  ends 
of  the  50-degree  cams  sufficiently  to  overlap  the  actual  roll  travel,  and 
at  the  same  time  we  increase  the  working  space  between  the  cams  to  allow 
the  roll  to  pass  through.  As  these  roll  spaces  between  the  cams  are 
later  taken  into  consideration  in  our  calculations  for  determining  the 
actual  distance  around  the  periphery  of  the  drum  consumed  by  the  50- 
degree  cams,  we  can  disregard  altogether  the  portions  of  these  cams 
extending  outside  of  lines  i  and  /.  Now,  as  there  are  four  forward  and 
backward  movements  to  complete  the  cycle  of  operations,  the  total  tur- 
ret travel  to  and  fro  may  be  represented  by  a  quantity  equal  to  8  X  dis- 
tance i  to  ?,  or  8  X  2\  inches  =  18  inches.  According  to  the  table  giving 
the  feeds  of  the  four  tools  to  be  used,  2xV  inches  of  turret  travel  is 
required  in  the  cutting  operations;  the  distance  from  k  to  I  being  If  inches 
the  total  indexing  travel  is  obviously  4Xl|  =  6^  inches.  From  the  18 
inches  which  we  have  taken  as  representing  the  total  travel  of  the  turret 
slide,  therefore,  must  be  deducted  2^^^  -\-  Q\  inches,  leaving  9yV  inches 
travel  controlled  by  the  50-degree  cams,  which,  as  previously  stated, 
are  generally  used  for  non-cutting  and  non-indexing  movements.  The 
peripheral  drum  space  occupied  by  these  cams  is  then  equal  to  O^V  X 
cotangent  of  50  degrees,  or  9.0625  inches  X  0.84  =  7.61  inches. 

If  the  cam  roll  m  is  13.  inches  in  diameter,  and  we  allow  ^-inch  clear- 
ance, we  have  as  the  perii)herai  distance  occupied  by  these  cam  spaces 
8  X  li  inch  X  cosecant  of  50  degrees  or  10  inches  X  1-3  =  18  inches. 
The  eight   ^-inch  flats  on  the  ends  of  the  cams  =  2  inches  peripheral 


COMPUTIXC;    THE   CUTTLNC;    AND    LNDEXLVO    CAM    ANGLES  17 

drum  space  utilized  in  this  fashion.  The  total  circumference  of  the 
drum,  48  inches,  —  7.61  inches  —  1."^  inches  —  2  inclies  leaves  25.39 
inches  peripheral  space  on  the  drum  available  for  the  cams  whose  angles 
have  to  be  computed. 

COMPUTING    THE    CUTTING    AND    INDEXING    CAM    ANGLES 

We  have  now  this  space  of  2o.39  inches  measui'eil  lengthwise  of  the 
cam  drum  surface  to  utilize  for  the  cutting  and  indexing  cams.  The  next 
thing  to  determine  is  tiie  number  of  revolutions  of  spindle  required  for 
the  several  operations  on  (ho  i)iece  of  work.  This  is  calculated  as  below 
from  the  data  in  Table  2. 

1st  tool.  Travel  of  turret,  0.2.J0"    at  0.004  feed  per  revolution  =     G2.5  rev. 

2d    tool.  Travel  of  turret,  0.9375"  at  0.00.5  feed  jkt  revolution  =  1S7..'>  rev. 

3d   tool.  Travel  of  turret,  0.62.")"     at  0.010  feed  per  revolution  =    02..5  rev. 

4th  tool.     1st  part  of  travel  of  turret,  0..59.37"  at  0.015  feed  per  revolution  =    39.5  rev. 

2d  part  of  travel  of  turret,  0.0312"  at  0.005  feed  per  revolution  =      6.2  rev. 

Indexing.   Travel  of  turret.  6.5"        at  0.04    feed  per  revolution  =  162.5  rev. 

Total  number  of  revolutions  nece.ssary  =  520.7 

Table  2.  —  Spindle  Revolutions  Required  in  Making  Piece  Shown  in  Fig.  9 

Thus  we  find  that  for  the  25.39  inches  of  drum  periphery  available 
for  the  cams  to  be  figured,  the  spindle  should  make  521  turns,  or  20.5 
turns  for  each  inch  of  cam-drum  space.  This  spindle  velocity  per  inch  of 
drum  space  will  be  approximated  very  closely  by  using  on  the  counter- 
shaft a  10-inch  driving  drum  for  the  spindle  and  a  6-inch  pulley  for  driv- 
ing the  feed  motion.  The  question  of  spindle  and  feed-pulley  ratios  is 
discussed  more  fully  later  on. 

Knowing  the  feed  per  revolution  for  each  tool,  we  find  the  angle  for 
the  cam  for  that  tool  by  multiplying  the  rate  of  feed  by  20.5  which  gives 
the  tangent  of  the  desired  angle. 

The  angles  for  the  various  cams  are  then  as  follows: 

First  tool.  0.004"  feed  X  20.5  =  0.082     =  tangent  of    4°  42' 

Second  tool.  0.005"  feed  X  20.5  =  0.1025  =  tangent  of    5°  51' 

Third  tool.  0.010"  feed  X  20.5  =  0.205     =  tangent  of  11°  36' 

Fourth  tool.  0.015"  feed  X  20.5  =  0.3075  =  tangent  of  17°    5' 

Fourth  tool.  0.005"  feed  X  20.5  =  0.1025  =  tangent  of    5°  51' 

Indexing.  0.04"    feed  X  20.5  =  0.82      =  tangent  of  39°  21' 
Table  3.  —  Cutting  and  Indexing  Cam  Angles 

The  angles  having  been  doternuned,  the  cams  may  now  be  laid  out 
on  the  full-size  drawing,  a  space  n.  Fig.  S,  equal  to  the  roll  tliameter  plus 
^-inch  clearance  being  left  between  the  adjacent  cams,  and  the  flats  of 
^-inch  which  prevent  wearing  of  the  cam  corners  being  left  on  the  working 
ends  of  each  cam.  A  layout  of  these  cams  to  a  larger  scale  (about  ^ 
actual  size)  is  presented  in  Fig.  10,  and  in  this  drawing  the  angles  of  the 


18        CAMMING  THE  PRATT  &  WHITNEY  AUTOMATIC  SCREW  MACHINE 

cams  are  all  shown.  While  these  angles  are  given  in  degrees  and  min- 
utes, the  nearest  half  degree  is  sufficiently  close  in  practice.  It  may  be 
of  interest  at  this  point,  before  considering  the  forming  and  cut-off  cams, 
to  show  diagrammatically  how  the  cam-drum  surface  is  divided  among 
the  various  cams  which  have  been  just  laid  out.  For  this  purpose  Figs. 
11  to  15  inclusive  have  been  drawn,  although  of  course  such  diagrams 
would  not  be  actually  used  in  the  working  out  of  the  camming  problem. 
The  portions  of  the  50-degree  cams  used  in  the  foregoing  calculations 
are  here  shown  transferred  below  to  the  similar  drum  surface  in  Fig.  11, 
where  a  series  of  triangles  1,  2,  3,  4,  5,  etc.,  are  drawn  which  when  ar- 
ranged in  the  order  shown  in  Fig.  12  indicate  the  forward  and  backward 
movement  of  the  turret  due  to  that  portion  of  the  50-degree  cams  which 
entered  into  the  previous  calculation,  giving  OjV  inches.  The  18-inch 
vertical  line  on  which  this  9^^  iiich  travel  is  laid  off  represents  the  total 
travel  of  the  turret  back  and  forth  between  the  lines  i  and  /  or  8  X  2^ 
inches.  Hence  the  8||  inch  portion  of  that  line  represents  that  amount 
of  turret  travel  due  to  the  cutting  and  index  cams.  Fig.  13  is  drawn  to 
double  the  scale  of  the  other  diagrams  to  show  more  clearly  the  flats  and 
roll  spaces.  Figs.  14  and  15  show  the  eight  roll  spaces  and  the  cam  fiats 
added  to  the  peripheral  distance  utilized  by  the  50-degree  cams,  and  the 
latter  sketch  indicates  the  amount  of  drum  space  actually  left  for  the  cut- 
ting cams  and  the  index  cams,  which  has  previously  been  found  to  be 
25.39  inches. 

FINDING    THE    CAM    ANGLES    GRAPHICALLY 

If  preferred,  the  angles  of  the  various  cams  may  be  obtained  without 
reference  to  tables  of  trigonometrical  functions.  Although  this  method 
of  finding  the  angles  is  very  convenient,  many  will  prefer  the  method 
given  below  \Vhich  does  not  involve  the  use  of  trigonometry.  A  hint  of 
this  is  given  in  Fig.  12.  Say  we  draw  a  perpendicular  line  .1,  Fig.  16,  on 
the  drawing  board  9iV  inches  long,  representing  the  to-an-fro  travel 
between  lines  i  and  I  by  50-degree  cams,  then  draw  a  horizontal  base  line 
B,  to  which  we  draw  a  line  C,  from  the  top  of  the  vertical  line  forming 
an  angle  of  50  degrees  with  the  horizontal  base  line.  The  portion  of  the 
latter  thus  cut  off  will  indicate  the  space  measured  around  the  drum 
which  the  50-degree  cams  between  lines  i  and  I  occupy,  or  7.61  inches 
which  can  be  measured  with  a  scale  accurately  enough  for  all  prac- 
tical purposes. 

Next  we  wish  to  determine  the  peripheral  distance  occupied  by  each 
cam-roll  space  and  can  find  this  by  a  similar  process  of  laying  out  the  roll 
between  the  ends  of  two  cams  as  at  D,  in  Fig.  17.  If  the  layout  is  made 
double  or  four  times  the  actual  size,  the  result  obtained  by  scaling  will 
be  more  accurate  and  in  fact  quite  near  enough  to  the  figured  distance. 
Multiplying  the  distance  D  by  8  will  give  us  the  space  required  by  the 


/ 


p 


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how  the  Turret-Slide  Drum  Surface  is  UtiliKed  by  Ibe  VarlouB  CamB,  Roll  Spaces,  ( 


n\ 


FINDING    THE   CA.Nl    ANGLES   (JKAPllICALLY 


19 


loox  Jp 


to 


20       CAMMING  THE  PRATT  &  ^VHTTNEY  AUTOMATIC  SCREW  MACHINE 

eight  cam-roll  spaces,  and  adding  this  to  7.61  inches  plus  2  inches  for  the 
eight  ^-inch  flats  on  the  cam  ends  gives  us  the  total  amount  to  subtract 
from  48  inches  (the  circumference  of  the  tlrum)  to  obtain  the  amount 
left  for  the  cutting  and  indexing  cams  (or  25.39  inches).  We  have  already 
found  that  the  spindle  makes  521  turns  during  the  travel  of  the  drum 
through  a  distance  of  25.89  inches,  or  20.5  turns  per  inch  of  drum  travel. 
By  referring  back  to  our  figures  in  Table  2,  we  see  that  the  first  tool  will 
require  62.5  revolutions  in  feeding  its  distance  of  0.250  inch  toward  the 
chuck  at  0.004  inch  per  revolution.  In  other  words,  this  tool  will  require 
a  drum  travel  of  (62.5  divided  by  20.5)  or  3.05  inches.  Laying  off  a  line 
of  this  length  as  E,  in  Fig.  18,  and  drawing  a  perpendicular  of  0.250  inch 
to  represent  the  feed  distance,  we  have  then  mereh'  to  measure  the 
angle  with  the  protractor  which  will  give  us  at  once  the  correct  angle 
for  this  cam.  The  angles  of  all  the  other  cams  may  be  obtained  by  a  sim- 
ilar process,  the  side  F  of  the  triangle  laid  out  representing  the  total 
feed  or  turret-slide  travel  required  for  the  cam  in  question,  and  the  length 
E  representing  the  distance  in  inches  which  the  drum  travels  while  the 
spindle  is  making  the  number  of  revolutions  necessary  for  that  particular 
operation,  as  shown  by  Table  2.  As  suggested,  it  will  be  well  to  make 
the  layout  double  size  or  larger,  thus  minimizing  the'  possibility  of  error 
in  scaling  the  lines  and  measuring  the  angle. 

THE    FORMIXG    AND    CUTTING-OFF    CAMS 

Returning  now  to  the  forming  and  cutting-off  cams,  Fig.  8  shows  these 
members  laid  out  on  the  opposite  sides  of  their  disk.  The  forming  tool 
cuts  down  the  neck  and  fillet  at  the  rear  of  the  piece  Fig.  9  and  should  be 
fed  at  about  0.002  inch  per  revolution,  the  operation  being  performed 
at  the  same  tinie  as  the  drilling.  We  have  found  that  the  spindle  makes 
20.5  revolutions  to  every  inch  of  turret-slide  drum  travel,  and  this  means 
that  in  a  forming  movement  of  ^  inch  or  0.125  inch  at  0.002  inch  per  turn, 
we  require  62^  revolutions,  which  is  ec^uivalent  practically  to  3  inches  of 
drum  travel.  Laying  off  this  amount  on  the  drum  T,  we  can  run  the 
radial  lines  indicated  to  the  center  of  the  cam  disk  to  define  the  limits  of 
the  forming  cam  o.  Li  drawing  the  working  edge  of  the  cam  we  strike 
a  curve  giving  a  throAV  somewhat  greater  than  ^  inch,  according  to  the 
location  of  the  pin  on  which  the  cross-slide  operating  arms  are  pivoted. 
Thus,  if  the  upper  end  of  the  rocker  arm  is  f  the  length  of  the  lower,  it 
means  practically  that  for  every  0.001  advance  of  the  cam  slide  the  lower 
end  of  the  arm  must  move  outward  about  0.0013  inch.  The  forming 
movement  of  0.125  inch  requires  then  a  cam  throw  of  0.1625. 

In  cutting  off  the  completed  work  a  feed  of  about  0.0025  inch  per 
revolution  will  be  suitable.  If  the  thickness  of  the  metal  plus  a  reason- 
able amount  for  clearance,  etc.,  is  equal  to  |  inch,  the  work  will  make 


SPINDLE   DPJ'M   AND    FEED    PULLEY  CONSIDERATIONS  21 

50  revolutions  during  the  operation;  at  20.5  revolutions  of  the  spindle 
per  inch  of  turret-slide  drum  travel  tiie  travel  of  the  drum  during  the 
operation  of  the  cut-off  cams  will  be  approximately  22  inches.  This 
operation  may  commence  at  or  slightly  before  the  completion  of  the 
finish  counterboring  as  shown  in  Fig.  8,  where  the  cut-off  cam  ;)  is  drawn 
in  on  its  side  of  the  disk  in  the  same  manner  as  the  forming  cam  just 
described.  With  the  cam  slide  levers  pivoted  at  the  point  mentioned  in 
connection  with  the  forming  cam  the  cut-off  movement  of  ^  inch  will 
require  a  cam  throw  of  about  0.166  inch. 

It  will  be  obvious  that  the  turret-slide  drum  must  have  sufficient  .space 
between  the  points  where  the  cut-off  operation  is  completed  and  the  first 
operation  on  the  next  piece  is  commenced  to  allow  for  the  opening  of 
the  chuck,  the  feeding  of  the  stock,  and  the  locking  up  of  the  chuck  on 
the  work. 

This  distance  is  indicated  cleaily  in  Fig.  8. 

In  putting  the  cams  on  the  turret-slide  drum  the  correct  starting  posi- 
tion for  the  first  cam  can  be  easily  located  by  squaring  across  from  the 
locking-up  cam  on  the  chucking  drum,  which  cam  must  close  the  chuck 
tight  before  the  first  tool  is  brought  quite  into  working  position.  Where 
a  stop  is  used  in  the  first  hole  in  the  turret  the  stop  cam  on  the  drum  is 
so  located  relatively  to  the  chucking  cams  as  to  bring  the  stop  to  its 
extreme  forward  position  just  before  the  stock  is  fed  completely  out  and 
the  chuck  closed. 

SPIXDLE    DRUM    A\D    FEED    PULLEY    COXSIDERATIOXS 

In  the  preceding  matter  it  has  been  shown  that  after  subtracting  from 
the  circumference  of  the  turret-slide  drum  the  peripheral  space  occupied 
by  the  50-degree,  or  non-cutting  and  non-indexing  cams,  the  eight  cam- 
roll  spaces  and  the  eight  ^-inch  flats  on  the  cam  ends,  we  have  left  a  cer- 
tain distance  available  for  the  cutting  and  indexing  cams  whose  angles 
have  to  be  figuretl  or  obtained  by  layout  and  measurement.  We  have 
found,  too,  that  during  the  rotation  of  the  drum  through  a  certain  dis- 
tance equal  to  the  space  occupied  by  these  cams,  the  spindle  should  make 
a  certain  number  of  revolutions  (as  per  Table  2)  determined  by  adding 
up  the  number  of  turns  nece.ssar}'  for  taking  the  different  turret-tool 
cuts  at  the  desired  rates  of  speed,  plus  the  turns  during  the  indexing 
movements.  In  order,  therefore,  that  the  spindle  and  cam  drum  shall  be 
driven  at  the  proper  relative  speeds,  with  any  given  ratio  of  gearing  in 
the  feed  motion,  the  question  of  the  relative  diameters  of  the  spindle- 
driving  drum  on  the  countershaft  and  the  feed-motion  driving  pulley 
on  the  same  counter  has  to  be  taken  into  consideration.  For  it  is  obvious 
that,  both  spindle  and  feed  motion  being  belted  from  the  one  counter- 
shaft, if  we  are  using  say  a  certain  diameter  of  counter  drum  for  driving 


22       CAMMING  THE  PRATT  A-  WHITNEY  AUTOMATIC  SCREW  MACHINE 


the  spindle,  any  change  in  the  size  of  pulley  for  driving  the  feed  motion 
will  affect  the  rate  of  turret-slide  feed  per  revolution  of  spindle. 

SPINDLE    AXD    FEED-DRIVE    RATIOS 

In  Fig.  19  is  shown  by  diagram  the  arrangement  of  pulleys  on  counter- 
shaft, spindle,  and  feed  motion,  ,4.  being  the  drum  for  dri^•ing  the  spindle 
in  either  direction  through  reversing  belts  running  on  spindle  pulley  B, 
which  is  located  between  two  loose  pulleys;  C  is  the  countershaft  pulley 
(known  as  the  "feed  pulley")  for  driving  the  cam-drum  shaft  D  through 
pulley  E,  which  operates  the  worm  shaft  and  worm  gear  F  at  slow  speed 
through  the  planetary  gearing  indicated  at  G,  or  directly  at  high  speed 
by  a  clutch  connecting  the  pulley  directly  to  the  worm  shaft.  On  the 
No.  1  machine,  for  example,  the  spindle  pulley  B  has  a  diameter  of  6f 
inches,  and  the  feed-motion  pulley  £"  is  6  inches.  The  worm  gear  has  84 
teeth  meshing  with  a  triple-thread  worm,  and  28  turns  of  the  worm  shaft 
are  required  to  drive  the  cam  shaft  and  cam  drums  through  one  complete 

c 


Counter 

— 

-1 

Shaft 

_ 

- 

Center  ol  Spindle 


J 

Cam  Shaft 

vfi 

D 

Fig.   19.  —  Diagram  of  Spindle  and  Cam- 
shaft Drive 

revolution.  With  a  24  to  1  ratio  of  gearing  in  the  feed  drive  at  G,  it  is 
obvious  that  the  pulley  E  must  turn  24  X  28  times,  or  672  turns  to  each 
revolution  of  the  drum  shaft  —  assuming,  of  course,  that  the  slow  mo- 
tion (24  to  1)  is  in  operation  throughout  the  complete  cycle.  The  cir- 
cumference of  the  turret-slide  drum  H  carried  by  the  latter  being  48 
inches,  for  each  inch  of  peripheral  travel  of  the  drum,  the  pulley  E  on  the 
feed  drive  must  turn  (672  -^  48)  =  14  revolutions.  If  we  have  (as  found 
in  connection  with  Table  2)  a  peripheral  distance  of  25. .39  inches  to  travel 
during  521  turns  of  the  spindle  in  order  to  give  the  required  feeds  with 
the  cams,  as  figured  out,  the  spindle  must  make  20.5  revolutions  for  each 
inch  of  drum  travel.  That  is,  while  pulley  E,  Fig.  19,  is  making  14  revo- 
lutions, pulley  B  must  make  20.5  revolutions.     If  the  two  pulleys  were 


USE   OF   Tin:   TABLES  23 

of  the  same  diameter,  the  diameter  of  the  countershaft  drum  A  and  feed 
pulley  C  would  of  course  be  in  the  ratio  of  20.5  to  14  or  1.46  to  1.  The 
spindle  pulley,  however,  is  6|  inches  diameter  and  the  worm-shaft  pulley 
K  6  inches;  therefore  the  countershaft  pulleys  will  be  in  the  ratio  of  (20..5 
X  6g)  to  (14  X  6)  =  136  to  84,  or  a  ratio  of  1.62  to  1.  This  ratio  will 
be  approximated  very  closely  by  a  spindle-driving  drum  of  a  diameter 
of  10  inches  and  a  feed  pulley  of  6  inches. 

The  foregoing  matter  has  been  presented  in  order  to  show  the  rela- 
tion existing  between  the  speed  of  the  spintUe  and  the  speed  of  the  cam- 
drum  drive.  In  practice,  the  diameter  of  the  feed  pulley  required  to  be 
used  in  conjunction  with  any  given  diameter  of  driving  drum  for  the 
spindle  may  be  more  directly  obtained  by  the  aid  of  a  simple  table  — 
like  Table  4,  5,  6,  or  7  on  pages  29  to  32.  After  we  have  found  our  cam 
angles  as  already  described,  we  may  take  the  angle  of  any  one  of  the'cutting 
cams  and  use  this  in  connection  with  our  table  for  finding  the  required 
size  of  feed  pullcv. 

USE    OF   THE    TABLES 

Referring  now  to  Table  5.  this  table  is  arranged  with  cdlunnis  for  each 
feed-motion  ratio  from  24  to  1  down  to  2.7  to  1.  The  quantities  in  these 
columns  are  obtained  by  dividing  the  tangent  of  the  angles  from  1  to 
45  degrees  in  the  second  column  by  the  feed-pulley  constants  12.7,  5.91, 
etc.,  given  at  the  heads  of  the  respective  columns.  The  feed-pulley  con- 
stant, it  should  be  noted,  is  equivalent  to  the  numl)er  of  revolutions  of 
the  head  spindle  to  each  inch  of  peripheral  travel  of  the  turret  drum, 
with  the  same  diameter  of  pulleys  on  the  counter  for  driving  the  spindle 
and  the  feed  mechanism.  As  indicated  by  the  formula  at  the  bottom 
of  the  table,  the  feed  per  revolution 

tan.  of  angle  feed  pulley 

X 


feed-pulley  constant        counter  drum 

and  as  the  six  columns  under  the  respective  i-atios  are  already  worked 
out  giving  the  efjuivalent  of 

tan.  of  angle 
feed-pulley  constant 

the  feed  per  revolution  foi*  any  cam  angle  with  any  given  ratio  of  gearing 
in  the  feed  motion  is  found  by  multiplying  the  (juantity  opposite  the  angle 
and  in  the  required  colunm  by  the  feed-imlley  diameter  and  then  dividing 
by  the  diameter  of  the  counter  drum  driving  the  head  spindle. 

Now,  with  a  given  diameter  of  counter  drum  for  the  spindle,  and  with 
the  angle  determined  for  any  cam  and  the  rate  of  feed  given  which  we 
wish  to  })roduce  with  that  cam,  we  can  find  the  diameter  of  feed  pulley 
required  to  proiluce  that  rate  of  feed  l)y  a  formula  as  follows: 


2i       CAMMING  THE  PRATT  &  WHITNEY  AUTOMATIC  SCREW  MACHINE 

Dia.  feed  pulley  =  feed  per  rev.  X  dia.  counter  drum 

tan.  of  angle        \ 
feed-pulley  constant/ 
As  we  have  the  ex^Dression 

tan.  of  angle 
feed-pulley  constant 

already  worked  out  in  the  table  for  the  various  angles,  it  is  merely  neces- 
sary to  multiply  the  feed  per  revolution  by  the  diameter  of  the  drum 
for  driving  the  spindle,  and  divide  by  the  quantity  opposite  the  cam 
angle  under  the  proper  column.  Thus,  if  one  of  the  cams  in  the  set  which 
we  have  already  figured  out  is  to  give  a  rate  of  feed  of  0.005  inch  per  turn 
of  spindle  (using  the  24  to  1  ratio)  the  cam  angle  being  practically  6 
degrees,  and  if  we  are  using  a  10-inch  drum  on  the  countershaft  for  driving 
the  spindle,  we  can  find  the  size  of  the  feed  pulley  recjuired  by  multiply- 
ing 0.005  X  10  =  0.05  and  dividing  by  0.00S27  (found  opposite  6  degrees 
and  in  the  24  to  1  ratio  column)  =  6.  Hence  a  6-inch  pulley  is  the  proper 
size  to  use.  It  will  be  obvious  that  owing  to  the  method  used  in  deter- 
mining the  angles  of  the  set  of  cams  for  the  turret-slide  drum,  it  makes 
no  difference  whatsoever  which  cam  is  used  as  a  basis  for  working  out 
the  feed-pulley  diameter. 

Similar  tables  which  are  included  for  the  other  sizes  of  machines  should 
be  found  of  considerable  value. 

FEED    CHANGES 

The  figures  in  the  different  ratio  columns  in  Table  5  actually  show 
the  rates  of  feed  per  i-evolution  of  spindle  which  would  be  obtained  if 
the  feed  pulley  and  spindle-driving  drum  on  the  countershaft  were  of  the 
same  diameter,  and  by  following  across  the  table  on  any  horizontal  line 
the  possible  variations  obtainable  by  the  six  different  ratios  of  gears  for 
use  in  the  feed  mechanism  will  be  clearly  seen.  The  actual  feed  changes 
produced  by  different  angles  of  cams  and  various  sizes  of  feed  pulleys 
and  counter  drum  with  a  given  ratio  of  gearing  are  shown  by  Tables  8 
to  11.  Table  9,  for  example,  is  worked  out  for  the  No.  1  automatic  and 
for  a  24  to  1  ratio  of  feed  gearing,  and  it  will  be  apparent  from  this  talkie 
that  very  fine  changes  of  feed  are  obtained  with  any  given  feed  pulley 
and  counter  drum  by  slight  modification  in  cam  angles;  the  entire  range, 
of  course,  being  greatly  increased  when  we  introduce  the  gears  of  other 
ratios  into  the  feed  drive. 

It  should  be  borne  in  mind  that  after  the  machine  has  been  cammed 
in  accordance  with  the  method  descril^ed,  the  rate  of  feed  per  turn  of 
spindle  derived  from  the  cam  may  be  increased  or  decreased  by  changing 
the  gears  in  the  feed  motion  without  affecting  the  rate  of  turret-slide 


THE   TAVO-SPEED   SPINDLE    DRIVE  25 

travel  during  the  indexing  movement.  This  is  due  to  the  fact  that  the 
indexing  is  accomplished  with  the  feed-motion  pulley  clutched  direct 
to  the  cam  shaft  for  driving  the  cam  drum,  that  is,  the  "fast  motion" 
is  then  in  operation  and  this  drives  at  a  constant  speed  unless  the  feed 
pulley  on  the  countershaft  is  changed,  or  the  speed  of  the  counter  itself 
altered  by  shifting  the  position  of  the  belt  on  the  three-step  driving  cone. 
While  the  indexing  cams  are  laid  out  for  performing  their  work  with  the 
turret  slide  traveling  at  about  20  feet  per  minute,  some  departure  may 
be  allowed  either  way  from  this  normal  rate,  such,  for  instance,  as  might 
be  due  to  a  slight  change  in  diameter  of  feed  pulleys. 

THE    TWO-SPEED    SPINDLE    DRIVE 

It  is  quite  common  practice  now,  with  the  Pratt  &  Whitney  automatic, 
to  equip  it  with  a  two-step  pulley  for  operating  the  head  spindle  in  place 
of  the  single-diameter  drum  formerly  used  for  this  type  of  machine.  This 
gives  the  spindle  two  rates  of  speed  (ordinarily  2  to  1)  and  the  higher 
speed  is  generally  employed  for  the  backing  belt.  Thus,  a  suitable 
countershaft  speed  may  be  selectetl  for  the  rough  turning  cut  and  for 
threading,  using  the  forward  belt  (except  in  very  unusual  cases  where 
a  left-hand  thread  is  to  be  cut),  and  the  fast  backward  speed  is  then 
utilized  for  finish  turning  and  cutting  off,  a  left-hand  finishing  box 
tool  being  used  and  the  cut-off  being  carried  on  the  rear  end  of  the  cross 
slide.  If  a  forming  tool  is  required,  this  is  carried  at  the  front  of  the  cross 
slide  and  operated  while  the  roughing  box  tool  is  cutting,  with  the  spindle 
operating  at  its  slow  speed.  The  spindle  then  reverses  upon  the  com- 
pletion of  the  rough-turning  and  the  forming  operation,  and  runs  back- 
ward at  double  the  forward  speed  while  the  finishing  tool  is  in  operation. 
If  the  piece  is  to  be  threaded,  the  slower  forward  speed  is  utilized  while 
cutting;  and  after  the  die  has  run  on,  the  spindle  again  reverses  to  high 
speed  while  the  die  is  run  off  and  tlie  cut-off  tool  severs  the  work  from 
the  bar.  This  two-speed  arrangement  is  a  very  advantageous  one  as  it 
makes  it  possible  to  drive  the  spindle  at  speeds  best  adapted  for  the  cuts 
taken  by  the  different  classes  of  tools  used  on  the  work,  and  thus  greatly 
increases  the  output. 

In  plotting  out  cam  angles  for  use  in  connection  with  the  two-spindle 
drive  it  is  advisable  to  reduce  all  feeds  per  revolution  to  what  they  actu- 
ally would  be  in  case  only  one  of  the  two  speeds  was  used,  and  thus 
simplify  the  problem. 

For  example,  if  we  have  a  constant  feed  of  0.005  inch  per  revolution 
at  100  revolutions  per  minute,  and  another  constant  feed  of  0.005  inch 
at  200  revolutions  per  minute,  it  is  advisable  to  consider  both  at  the  same 
number  of  revolutions  per  minute.  To  reduce  the  former  to  the  latter 
=  0.005  inch  X  iS!}  or  0.0025-inch  feed  at  200  revolutions  per  minute, 


26       CAMMING  THE  PRATT  c^-  WHITNEY  AUTOMATIC  SCREW  MACHINE 

while  the  latter  would,  of  course,  remain  0.005.  The  tangents  of  the  angles 
for  the  cams  to  be  used  would,  of  course,  be  2  to  1,  while  the  actual  feeds 
per  revolution  at  the  speeds  used  are  equal. 

Fig.  20  shows  a  cam  layout  for  a  machine  using  the  two-speed  spindle 
drive,  the  turret-cam  drum  surface  development  being  shown  in  two 
sections  for  convenience.  The  forming  and  cutting-off  cams  are  sketched 
in  at  the  side  of  the  drum  layout  with  the  circles  drawn  to  clearly  indi- 
cate where  the  forming  and  cut-off  operations  commence  and  end.  The 
cams  shown  are  suitable  for  general  screw  work,  the  first  cam  A  being  a 
plain  50-degree  stop  cam  which  holds  the  turret  in  its  forward  position, 
while  the  stock  feeds  out.  Cam  B  for  the  roughing-box  tool,  and  the 
forming  cam  on  the  cross-slide  disk,  are  in  operation  while  the  spindle 
runs  at  its  slow  speed,  and  cam  C  for  the  finishing  cut  feeds  the  finishing- 
box  tool  over  the  work  with  the  spindle  operating  at  its  fast  speed.  The 
slow  spindle  speed  is  used  while  the  die  is  run  on  by  cam  D,  and  the  fast 
speed  is  again  employed  during  the  cutting-off  operation.  It  will  be  no- 
ticed that  extra  space  is  left  between  the  end  of  the  die  cam  D  and  the 
last  draw-back  cam.  This  extra  clearance  is  provided  in  order  that  the 
die  may  have  ample  time  to  run  up  on  the  screw  and  reverse  before 
the  draw-back  cam  comes  into  action  against  the  turret-slide  roll.  Where 
an  opening  die  is  used,  mounted  in  a  sliding  holder,  the  die  cam  may  be 
made  shorter  as  indicated  by  the  dotted  lines. 

The  forming  tool  is  used  advantageously  on  regular  screw  work  for 
necking  down  at  each  side  of  the  head  while  the  roughing-box  tool  is  in 
operation.  This  reduces  the  work  of  the  cutting-off  tool  and  on  many  jobs 
relieves  the  box  tool  of  the  work  of  finishing  the  under  side  of  the  head. 

PUTTING    ON    THE    CAMS 

A  few  words  regarding  the  forming  and  placing  of  the  cams  in  posi- 
tion on  the  drums  and  cut-off  disk  may  not  be  out  of  place  here.  After 
the  angles,  lengths,  etc.,  have  been  found  the  cams  may  be  cut  from  the 
flat  stock  to  the  right  length  and  proper  angles  at  the  ends  by  means 
of  a  saw  in  the  milling  machine,  swiveling  the  vise  to  give  the  required 
angles  for  the  ends,  and  then  the  holes  for  the  tap  bolts  are  drilled,  after 
which  the  cams  are  bent  to  conform  to  the  curvature  of  the  drum.  Tough 
steel  that  will  admit  of  being  hardened  should  be  used,  and  after  the  pieces 
are  hardened  they  are  located  one  by  one  on  the  drum,  and  the  latter 
drilled  and  the  holes  tapped  for  the  tap  bolts  which  secure  the  cams 
in  place.  The  turret-slide  cams  are  located  in  the  right  positions  rela- 
tive to  the  chucking  drum  cams  by  squaring  across  from  the  chuck- 
closing  cam  on  that  drum,  this  giving  the  right  location  for  the  first 
cam  on  the  turret-slide  drum.  It  must  be  kept  in  mind  that  the 
chuck-closing  cam  must  close  the   chuck   completely  before   the   cutting 


PITTING   OX    THE    CAMS 


27 


28       CAMMING  THE  PRATT  &  WHITNEY  AUTOMATIC  SCREW  MACHINE 

part  of  the  first  cam  on  the  turret   drum   comes  into   contact   with   the 
cam  roll. 

The  forming  and  cutting-off  cams  are  located  on  their  disk  so  that  the 
ends  of  these  cams  are  just  passing  the  ends  of  the  cross-slide  levers  when 
the  points  on  the  turret  cams  marked  in  the  layout  "end  of  forming" 
and  "end  of  cut-off"  are  just  in  contact  with  the  turret-slide  roll.  The 
idea  will  be  clear  from  the  drawing  in  Fig.  20. 


PRATT  &  WHITNEY  CAM  AND   FEED  TABLES 


29 


P.  &  W.  No.  0 

Automatic 


TANr.ENT  OF  ANGLE 


FEED 

PULLEY    CONSTANT 

RATIOS 

Tangent 


.0174G 
.02619 
.03492 
.04366 
.05241 
.06993 
.08749 
.10510 
.12278 
.14054 
.158.38 
.17633 
.19438 
.21256 
.23087 
.24933 
.26795 
.28675 
.30573 
.32492 
.34433 
.36397 
.3838(5 
.40403 
.42447 
.44523 
.46()31 
.48773 
.5095.3 
.53171 
.55431 
.57735 
.60086 
.62487 
.64941 
.67451 
.70021 
.72654 
.75355 
.78129 
.80978 
.83910 
.86929 
.90040 
.93252 
.96569 
1.00000 


24:1 


Feed 
Pulley 
Const. 

37.3 


.00046 

.00070 

.00093 

.00117 

.00140 

.00187 

.00234 

.00282 

.00329 

.(K)376 

.00424 

.00472 

.00521 

.00569 

.00618 

.00668 

.00718 

.00768 

.00819 

.00871 

.00922 

.00975 

.01029 

.01083 

.01137 

.01193 

.012.")() 

.01.^07 

.()l(i34 

.01425 

.01486 

.01547 

.01610 

.01675 

.01741 

.018.35 

.01877 

.01947 

.02020 

.02094 

.02170 

.02249 

.0233 

.0241 

.0250 

.0259 

.0268 


11.16:1 


Feed 
Pulley 
Const. 
17.35 


.0010 
.0015 
.0020 
.0025 
.0030 
.0040 
.0050 
.0060 
.0071 
.0081 
.0091 
.0101 
.0112 
.0122 
.0133 
.0143 
.0154 
.0165 
.0176 
.0187 
.0198 
.0209 
.0221 
.0233 
.0244 
.0255 
.0268 
.02S1 
.0293 
.0306 
.0319 
.0332 
.0346 
.0359 
.0374 
.0388 
.0403 
.0418 
.0434 
.0450 
.0466 
.0483 
.0500 
.0518 
.0537 
.0556 
.0576 


5.81:1 

Feed 
Pulley 
Const. 

9.03 


.0019 
.0029 
.0039 
.0048 
.0058 
.0078 
.0096 
.0116 
.01.36 
.0155 
.0175 
.0195 
.0215 
.0235 
.0256 
.0276 
.0297 
.0318 
.0339 
.0361 
.0382 
.0404 
.0426 
.0448 
.0471 
.0494 
.0517 
.0542 
.0565 
.0590 
.0615 
.0640 
.0667 
.0694 
.0720 
.0748 
.0777 
.0806 
.0836 
.0867 
.0899 
.0931 
.0964 
.0999 
.1034 
.1071 
.1107 


4:1 


Feed 
Pulley 
Const. 

0.22 

.0027 
.0042 
.0056 
.0069 
.0084 
.0113 
.0140 
.0169 
.0198 
.0225 
.0254 
.0283 
.0312 
.0341 
.0372 
.0401 
.0431 
.04(52 
.0493 
.0523 
.0554 
.0586 
.0(5  IS 
.0;55() 
.0(587 
.0716 
.0750 
.0786 
.0819 
.0856 
.0892 
.0929 
.0968 
.1006 
.1045 
.1085 
.1127 
.1169 
.1212 
.1257 
.1304 
.1351 
.1.399 
.1449 
.1500 
.1554 
.1608 


3.14:1 


Feed 
Pulley 
Const. 

4.88 

.0035 
.0053 
.0072 
.0088 
.0107 
.0143 
.0178 
.0215 
.0252 
.0287 
.0324 
.0361 
.0398 
.0435 
.0473 
.0510 
.0549 
.0588 
.0627 
.0666 
.0705 
.0746 
.0787 
.0828 
.08(59 
.0912 
.0955 
.1000 
.1043 
.1091 
.1136 
.1183 
.1232 
.1281 
.1330 
.1382 
.14.35 
.1488 
.1544 
.1601 
.1660 
.1720 
.1781 
.1845 
.1911 
.1978 
.2049 


Table  4. 


Correct  Feed  per  one  Revolution  of  Head  Spindle  = 

Tan,  of  Angle  Feed  Pulley 

Feed  Pulley  Const.        Counter   Drum 

For  Findinp;  the  Correct  Food  per  Rovolution  of  Spindle  or  the  Diameter 
of  Feed  Pulley,  for  any  f^iven  Cam  Aiiirle.     No.  0  Machine. 


30       CAMMING  THE  PRATT  &  WHITNEY  AUTOMATIC  SCREW  MACHINE 


P.  ct 

W.  No.  1 

rOMATIC 

TANGENT  OF  ANGLE 

Au 

FEED  PULLEY  CONSTANT 

Tangent 

RATIOS 

w 

24:1 

11.16:1 

5.81:1 

4:1 

3.1:1 

2.7:1 

Feed 

Feed 

Feed 

Feed 

Feed 

Feed 

w 

Pulley 

Pulley 

Pulley 

Pulley 

Pulley 

Pulley 

0 

Const. 

Const. 

Const. 

Const. 

Const. 

Const. 

12.7 

5.91 

3.07 

2.18 

1.64 

1.43 

1 

.01746 

.00137 

.00295 

.00568 

.00800 

.01084 

.01220 

1* 

.02619 

.00206 

.00443 

.00853 

.01201 

.01596 

.01831 

2 

.03492 

.00274 

.00591 

.01137 

.01601 

.02129 

.02441 

2* 

.04366 

.00343 

.00738 

.01422 

.02002 

.02662 

.03053 

3" 

.05241 

.00412 

.00886 

.01707 

.02404 

.03195 

.03665 

4 

.06993 

.00550 

.01183 

.02277 

.03207 

.04264 

.04897 

5 

.08749 

.00688 

.01480 

.02849 

.04013 

.05334 

.06118 

6 

.10510 

.00827 

.01778 

.03423 

.04821 

.06408 

.07350 

7 

.12278 

.00966 

.02077 

.04000 

.05401 

.07608 

.08586 

8 

.14054 

.01106 

.02378 

.04577 

.06447 

.08569 

.09828 

9 

.15838 

.01247 

.02679 

.05158 

.07265 

.09655 

.11075 

10 

.17633 

.01388 

.02983 

.05687 

.08000 

.10648 

.12200 

11 

.19438 

.01530 

.03289 

.06331 

.08916 

.11852 

.13593 

12 

.21256 

.01673 

.03596 

.06923 

.09750 

.12961 

.14864 

13 

.23087 

.01817 

.03906 

.07520 

.10590 

.14077 

.16144 

14 

.24933 

.01963 

.04218 

.08122 

.11437 

.15203 

.17435 

15 

.26795 

.02109 

.04533 

.08728 

.12291 

.16338 

.18737 

16 

.28675 

.02257 

.04851 

.09340 

.13153 

.17487 

.20053 

17 

.30573 

.02407 

.05173 

.09959 

.14024 

.18642 

.21380 

18 

.32492 

.02558 

.05494 

.10583 

.15863 

.19812 

.22721 

19 

.34433 

.02711 

.05995 

.11216 

.15795 

.20996 

.24078 

20 

.36397 

.02865 

.06158 

.11855 

.16695 

.22193 

.25453 

21 

.38386 

.03022 

.06495 

.12503 

.17608 

.23406 

.26843 

22 

.40403 

.03181 

.06836 

.13160 

.18533 

.24635 

.28253 

23 

.42447 

.03342 

.07182 

.13826 

.19470 

.25882 

.29613 

24 

.44523 

.03505 

.07533 

.14502 

.20423 

.27148 

.31135 

25 

.46631 

.03671 

.07890 

.15189 

.21390 

.28433 

.32609 

26 

.48773 

.03761 

.08252 

.15887 

.22372 

.29739 

.34107 

27 

.50953 

.04012 

.08621 

.16600 

.23373 

.31069 

.35631 

28 

.53171 

.04186 

.08996 

.17319 

.24390 

.32421 

.37183 

29 

.55431  , 

.04364 

.09379 

.18055 

.25427 

.33800 

.38763 

30 

.57735 

.04545 

.09769 

.18805 

.26483 

.35201 

.40374 

31 

.60086 

.04731 

.10166 

.19572 

.27562 

.36637 

.42018 

32 

.62487 

.04920 

.10573 

.20354 

.28633 

.38101 

.43697 

33 

.64941 

.05113 

.10988 

.21153 

.29789 

.39598 

.45413 

34 

.67451 

.05311 

.11413 

.21971 

.30941 

.41128 

.47168 

35 

.70021 

.05513 

.11837 

.22808 

.32119 

.42695 

.48965 

36 

.72654 

.05720 

.12293 

.23665 

.33327 

.44301 

.50807 

37 

.75355 

.05870 

.12750 

.24545 

.34566 

.45945 

.52695 

38 

.78129 

.06151 

.13219 

.25449 

.35839 

.47639 

.54635 

39 

.80978 

.06297 

.13701 

.26377 

.37147 

.49376 

.56628 

40 

.83910 

.06607 

.14198 

.27332 

.38491 

.51164 

.58678 

41 

.86929 

.06844 

.14709 

.28315 

.39876 

.53005 

.60789 

42 

.90040 

.07089 

.15218 

.29329 

.41302 

.54902 

.62965 

43 

.93252 

.07342 

.15778 

.30375 

.42730 

.56861 

.65211 

44 

.96569 

.07525 

.16338 

.31455 

.44297 

.58884 

.67531 

45 

1.00000 

.07881 

.16920 

.32573 

.45871 

.60975 

.69930 

C 

orrect  Feed 

per  one  Key 

solution  of  Head  Spindl 

6  = 

Tan 

.  of  Angle 

Feed  Pulley 

Feed  I 

'uUey  Const 

Counte 

r  Drum 

Table  5.  —  For  Finding  the  Correct  Feed  per  Revolution  of  Spindle  or  the  Diameter 
of  Feed  Pulley,  for  any  given  Cam  Angle.     No.  1  Machine. 


PRATT  &  WHITNEY  CAM  AND  FEED  TABLES 


31 


P.  &  W.  No.  2 
Automatic 


T.\NGEN'I^OF  ANGLE 

FEED   PULLEY   CONSTANT 


Tangent 

R.ATIOS 

u 

24:1 

11.10:1 

5.8:1 

4:1 

3:1 

2.6:1 

X 

Feed 

Feed 

Feed 

Feed 

Feed 

Feed 

Q 

Pulley 

Pulley 

Pulley 

Pulley 

Pulley 

Pulley 

Const. 

Const. 

Const. 

Const. 

Const. 

Const. 

10.9 

7.86 

4.08 

2.81 

2.11 

1.83 

1 

.01746 

.(X)103 

.0022 

.0042 

.0061 

.0081 

.0093 

1.V 

.02019 

.00154 

.0033 

.0064 

.0093 

.0123 

.0142 

2 

.03492 

.00206 

.0044 

.0086 

.0125 

.0166 

.0191 

2* 

.04366 

.00257 

.0055 

.0105 

.0153 

.0204 

.0234 

3 

.05241 

.00310 

.0066 

.0127 

.0185 

.0246 

.0283 

4 

.06993 

.00413 

.0089 

.0172 

.0249 

.0332 

.0382 

5 

.08749 

.00517 

.0110 

.0213 

.0310 

.0412 

.0474 

6 

.10510 

.00621 

.0133 

.0257 

.0374 

.0500 

.0572 

7 

.12278 

.00726 

.0156 

.0301 

.0438 

.0583 

.007(J 

8 

.14054 

.00831 

.0178 

.0343 

.0498 

.0664 

.07(53 

9 

.15838 

.00937 

.0201 

.0387 

.0562 

.0749 

.0801 

10 

.17633 

.01043 

.0224 

.0431 

.0627 

.0834 

.0959 

11 

.19438 

.01150 

.0246 

.0475 

.0691 

.0913 

.1057 

12 

.21256 

.01257 

.0269 

.0519 

.0755 

.1005 

.1155 

13 

.23087 

.01366 

.0293 

.0506 

.0822 

.1095 

.12.59 

14 

.24933 

.01475 

.0316 

.0010 

.0886 

.1180 

.1357 

15 

.26795 

.01585 

.0340 

.0657 

.0954 

.1270 

.1461 

16 

.28675 

.01696 

.0364 

.0703 

.1022 

.1.360 

.1.504 

17 

.30573 

.01809 

.0389 

.0750 

.1089 

.1450 

.lOOS 

18 

.32492 

.01922 

.0413 

.0796 

.1157 

.1541 

.1771 

19 

.34433 

.02037 

.0437 

.0843 

.1225 

.1031 

.1875 

20 

.36397 

.02153 

.0462 

.0892 

.1296 

.1725 

.1984 

21 

.38386 

.02271 

.0488 

.0941 

.1367 

.1820 

.2093 

22 

.40403 

.02390 

.0513 

.0990 

.1438 

.1915 

.2202 

23 

.42447 

.02511 

.0538 

.1039 

.1509 

.2010 

.2311 

24 

.44523 

.02693 

.0565 

.1090 

.1584 

.2109 

.2425 

25 

.46631 

.02759 

.0592 

.1142 

.1659 

.2209 

.2540 

26 

.48773 

.02885 

.0620 

.1197 

.1737 

.2313 

.2000 

27 

.50953 

.03014 

.0646 

.1247 

.1812 

.2413 

.2774 

28 

.53171 

.03146 

.0676 

.1303 

.1894 

.2522 

.2899 

29 

.55431 

.03279 

.0704 

.1357 

.1972 

.2626 

.3019 

30 

.57735 

.03416 

.0733 

.1414 

.2054 

.2735 

.3145 

31 

.60086 

.03555 

.0763 

.  .1472 

.2140 

.2849 

.3275 

32 

.62487 

.03697 

.0794 

.1531 

.2235 

.2963 

.3400 

33 

.64941 

.03842 

.0824 

.1590 

.2310 

.3076 

.3537 

34 

.67451 

.03991 

.0856 

.1651 

.2399 

.3195 

.3073 

35 

.70021 

.04143 

.0889 

.1715 

.2492 

.3318 

.3815 

36 

.72654 

.04299 

.0922 

.1779 

.2585 

.3431 

.3957 

37 

.75355 

.04458 

.0956 

.1845 

.2681 

.3569 

.4104 

38 

.78129 

.04623 

.0992 

.1913 

.2780 

.3702 

.425() 

39 

.80978 

.04791 

.1029 

.1985 

.2882 

.3839 

.4415 

40 

.83910 

.04965 

.1066 

.2056 

.2987 

.3977 

.4573 

41 

.86929 

.0514 

.1104 

.2129 

.3094 

.4119 

.4770 

42 

.90040 

.0533 

.1143 

.2205 

.3204 

.4266 

.4905 

43 

.93252 

.0552 

.1184 

.2283 

.3318 

.4418 

.5079 

44 

.96569 

.0572 

.1226 

.2364 

.3435 

.4574 

.5259 

45 

1.00000 

.0592 

.1272 

.2450 

.3560 

.4740 

.5450 

Correct  Feed  per  one  Revolution  of  Head  Spindle 
Tan  of  .\nsle  Feed  Pulley 

Feed  Pulley  Const.       Counter    Drum 


T.\.BLE   6. 


For  Finding  the  Correct  Feed  per  Revolution  of  Spindle  or  the  Diameter 
of  Feed  Pulley,  for  any  given  Cam  Angle.     No.  2  Machine. 


32       CAMMING  THE  PRATT  &  WHITNEY  AUTOMATIC  SCREW  MACHINES 


P.  &  \ 

V.  No.  3 

)MATIC 

TANGENT  OF  ANGLE 

AUTC 

FEED  PULLEY 

CONSTANT 

(open  belt)     I 

Tangent 

R.\TIOS 

H 

58:1 

21.9:1 

10.1:1 

8.19:1 

5.7:1 

4.2:1 

a, 
o 

Feed 

Feed 

Feed 

Feed 

Feed 

Feed 

w 

Pullev 

Pulley 

Pulley 

Pulley 

Pulley 

Pulley 

O 

Const. 

Const. 

Const. 

Const. 

Const . 

Const. 

32.9 

12.4 

9.1.3 

4.65 

3.23 

2..38 

1 

.01746 

.00053 

.00137 

.00186 

.00365 

.00526 

.00714 

1* 

.02619 

.00079 

.00209 

.00285 

.00559 

.00805 

.01092 

2" 

.03492 

.00106 

.00282 

.00383 

.00752 

.01083 

.01470 

2* 

.04366 

.00132 

.00346 

.00471 

.00924 

.01331 

.01806 

3" 

.05241 

.00159 

.00419 

.00569 

.01118 

.01610 

.02184 

4 

.06993 

.00212 

.00564 

.00766 

.01505 

.02167 

.02940 

5 

.08749 

.00265 

.00701 

.00953 

.01870 

.02693 

.03654 

6 

.10510 

.00319 

.00846 

.01149 

.02257 

.03250 

.04410 

7 

.12278 

.00373 

.00991 

.01347 

.02644 

.03808 

.05166 

8 

.14054 

.00427 

.01128 

.01533 

.03010 

.04334 

.05880 

9 

.15838 

.00481 

.01273 

.01730 

.03397 

.04891 

.06636 

10 

.17633 

.00535 

.01418 

.01927 

.03784 

.05448 

.07392 

11 

.19438 

.00590 

.01564 

.02124 

.04171 

.06006 

.08148 

12 

.21256 

.00646 

.01709 

.02321 

.04558 

.06563 

.08904 

13 

.23087 

.00701 

.01862 

.02529 

.04966 

.07151 

.09702 

14 

.24933 

.00757 

.02007 

.02726 

.05353 

.07709 

.10458 

15 

.26795 

.00814 

.02160 

.02934 

.05762 

.08297 

.11256 

16 

.28675 

.00871 

.02313 

.03142 

.06170 

.08885 

.12054 

17 

.30573 

.00929 

.02466 

.03351 

.06579 

.09473 

.12852 

18 

.32492 

.00987 

.02619 

.03558 

.06987 

.10062 

.13650 

19 

.34433 

.01046 

.02773 

.03767 

.07396 

.10650 

.14448 

20 

.36397 

.01106 

.02934 

.03986 

.07826 

.11299 

.15288 

21 

.38386 

.01166 

.03095 

.04205 

.08256 

.11888 

.16128 

22 

.40403 

.01228 

.03256 

.04424 

.08686 

.12507 

.16968 

23 

.42447 

.01290 

.03417 

.04643 

.09116 

.13127 

.17808 

24 

.44523 

.01353 

.03587 

.04873 

.09567 

.13777 

.18690 

25 

.46631 

.01414 

.03756 

.05103 

.10019 

.14427 

.19572 

26 

.48773 

.01482 

.03933 

.05344 

.10492 

.15108 

.20496 

27 

.50953 

.01548 

.04102 

.05573 

.10943 

.15758 

.21378 

28 

.53171 

.01616 

.04288 

.05825 

.11438 

.16470 

.22344 

29 

.55431 

.01684 

.04465 

.06066 

.11911 

.17151 

.23268 

30 

.57735 

.01754 

.04651 

.06318 

.12405 

.17864 

.24234 

31 

.60086 

.01826 

.04844 

.06581 

.12921 

.18607 

.25242 

32 

.62487 

.01896 

.05037 

.06844 

.13437 

.19350 

.26250 

33 

.64941 

.01973 

.05231 

.07106 

.13953 

.20093 

.27258 

34 

.67451 

.02050 

.05432 

.07380 

.14491 

.20867 

.28308 

35 

.70021 

.02127 

.05642 

.07665 

.15050 

.21672 

.29400 

36 

.72654 

.02208 

.05852 

.07949 

.15609 

.22477 

.30492 

37 

.75355 

.02290 

.06069 

.08245 

.16189 

.23312 

.31626 

38 

.78129 

.02374 

.06295 

.08552 

.16791 

.24179 

.32802 

39 

.80978 

.02461 

.06529 

.08869 

.17415 

.25077 

.34020 

40 

.83910 

.02550 

.06762 

.09187 

.18038 

.25975 

.35238 

41 

.86929 

.02642 

.07004 

.09515 

.18683 

.26804 

.36498 

42 

.90040 

.02736 

.07254 

.09855 

.19350 

.27864 

.37800 

43 

.93252 

.02833 

.07512 

.10205 

.20038 

.28854 

.39144 

44 

.96569 

.02934 

.07778 

.10566 

.20747 

.29876 

.40530 

45 

1.00000 

.03040 

.08060 

.10950 

.21500 

.30960 

.42000 

C( 

jrrect  Feed 
Tan 

per  one  Re"' 
of  Angle 

t^olution  of  '. 
^^      Feed 

iead  Spindl 
Pulley 

6  = 

Feed  Pulley  Const.        Counter   Drum 

Table  7.  —  For  Finding  the  Correct  Feed  per  Revolution  of  Spindle  or  the  Diameter 
of  Feed  Pulley,  for  any  given  Cam  Angle.     No.  3  Machine. 


PRATT  &   WHITNEY  CAM  AND  FEED  TABLES 


3.3 


5 

si 

O     2 
£     i 

> 
J 

g 

O 

a 

5 
s 
< 

o 

!M  re  It  o  1^  X  o  ei  T  t^  r:  re  -r  o  ~.  —  -r  o  o  o  re  o  O  u:  o 

(M  O  O  -T  X  Ti  1- ^  >-e  c;  re  X  ei  t^  '-e  't  -r  -r  —  -T  -r  -r  -.;;  l^  ^3 

•-1 .—  oi  ei  ei  re  re  -r  -T  -T  i-e  It  -.c  o  t>-  X  ~  O  O  "  01  re  T  't  '-O 

00000  000000000000.^-.-H^-H^  —  _ 
OOOOOOOOOOOOOOOOOOOOOOOOO 

^ 

00098 
00131 
001(54 
00197 
00230 
002(53 
002!)6 
00.330 
003(53 
00.3!)7 
00432 
0046(5 
00.501 
005.36 
00608 
00(581 
0075(5 
00832 
00872 
00!)  12 
00!)!  1 4 
01080 
01168 
01261 
01309 

3" 

.00073 
.00098 
.00123 
.00147 
.00172 
.00197 
.00222 
.00247 
.00273 
.002!)8 
.00323 
.00350 
.00376 
.00402 
.00456 
.00511 
.00567 
.00624 
.00654 
.00(584 
.00746 
.00810 
.0087(5 
.00946 
.00982 

l-Q 

00049 
000(55 
00082 
00098 
00115 
00131 
00148 
00165 
00182 
00199 
00216 
00233 
00251 
00268 
00304 
00340 
00378 
00416 
0043(5 
00456 
00497 
00540 
00584 
00631 
00655 

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li  to 

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ai    ^ 

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Ui  z 
to 

2 

s 

PL, 

a 

lu 
O 
a: 

S 
< 

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CHAPTER    III 

The  Brown  &  Sharpe  Automatic  Screw  Machine 

The  general  design  of  the  automatic  screw  machine  built  by  the  Brown 
&  Sharpe  Manufacturing  Company,  Providence,  K.  I.,  is  represented  in 
Figs.  21  and  22,  the  size  of  machine  illustrated  in  these  half-tones  being 
the  No.  00.  which  has  a  maximum  chuck  capacity  of  f\  inch,  and  a  max- 


FiG.  21.  —  Brown  i*i:  Sharpe  No.  00  Automatic  Screw  Machiiu 


imum  feed  of  2  inches;  the  greatest  length  that  it  will  turn  being  1|  inches. 
Various  features  of  construction  are  shown  clearly  in  the  line  drawings. 
Figs.  23  to  30.  Before  taking  up  the  construction  of  the  machine  in 
detail,  however,  it  may  be  well  to  outline  briefly  certain  features  brought 
out  by  the  half-tone  engravings. 

37 


38 


THE   BROWN    &   SHARPS   AUTO.MATIC   SCREW   MACHINE 


GENERAL    PRINCIPLES    OF    CONSTRUCTION 

The  system  of  cams  employed  on  this  type  of  machine  was  adopted 
by  the  Brown  &  Sharpe  Manufacturing  Company  a  number  of  3'ears  ago 
and  provides  for  a  set  of  cams  for  each  piece  to  be  matle,  so  that  when  a 
given  piece  is  to  be  undertaken  it  is  simply  necessary  to  place  a  set  of 
cams  for  this  piece  in  position;  the  machine  is  then  ready  to  operate, 
except  for  the  necessary  adjustments  of  the  turret  tools  and  cross-slide 
tools. 


Fig.  22.  —  Brown  &  Sharpe  Automatic  Screw  Machine  (Rear  View) 

The  turret  is  arranged  for  six  tools;  there  are  front  and  rear  cross  slides, 
which  are  operated  by  edge  cams  made  from  blanks  4j  inches  diameter 
with  1-inch  center  hole  and  |-inch  locating-pin  hole.  These  locating- 
pin  holes  are  also  placed  for  positioning  the  cams  and  insure  their  being 
located  in  the  proper  position  to  give  correct  timing. 

The  turret-slide  cam  is  carried  on  shaft  A,  Fig.  22,  the  end  shown 
being  the  shank  of  the  clamp  nut.     This  cam  is  placed  on  the  shaft  through 


THE   SPIXDLE   REVERSE  39 

an  opening  in  the  rear  end  of  the  macliine,  which  gives  ready  access  to 
this  adjustment.  The  cross-slide  cams  are  carried  on  the  front  shaft  at 
B  and  C,  Fig.  21.  The  dogs  for  controlling  the  mechanism  for  reversing 
the  spindle,  opening  and  closing  the  chuck,  feeding  the  stock  and  rotating 
the  turret,  can  be  adjusted  on  carriers,  D,  E  and  F;  this  feature  gives  ease 
of  adjustment  for  all  operations  within  the  capacity  of  the  machine.  The 
turret-rotating  mechanism  draws  the  turret  slide  to  the  rear  position 
when  indexing  the  turret,  irrespective  of  the  hight  of  the  cam  position. 
This  does  awa}'  with  the  necessity  of  cutting  the  cams  back  to  allow  the 
tools  clearance  when  rotating.  The  reversing  shaft,  with  carrier  D,  can 
be  uncoupled  from  the  front  shaft  for  the  purpose  of  placing  the  cross- 
slide  cams  on  carriers  B  and  C.  The  stock  feed  can  be  adjusted  by  crank 
G,  and  the  change  gears  for  obtaining  different  cam-shaft  speeds  are 
mounted  on  shafts  H  and  /,  the  gear  marked  H  being  the  driver  and 
that  marked  /  the  driven.  The  latter  is  mounted  on  a  worm  shaft  at 
the  rear  of  the  machine,  which  drives  through  a  worm  gear  a  short  shaft 
running  crosswise  of  the  bed  to  the  front  of  the  machine  where  it  is  con- 
nected by  bevel  gears  with  the  front  shaft  or  cross-slide  cam  shaft.  It 
also  drives  b}'  means  of  spur  gears  the  shaft  A  on  which  is  carried  the 
turret-slide  cam. 

THE    SPIXDLE    AND    ITS    CLUTCHES 

The  front  elevation.  Fig.  23,  gives  a  longitudinal  section  through  the 
spindle  and  its  boxes.  This  spindle,  which  has  hardened,  ground,  and 
lapped  bearings,  runs  in  boxes  of  phosphor  bronze,  the  front  box  having 
a  tapered  exterior,  and  provision  for  taking  up  wear.  End  play  may 
be  taken  up  by  adjusting  nuts  located  at  the  rear  box. 

The  spindle  is  driven  by  friction  clutch  pulleys  having  hardened  steel 
bushes  and  roller  bearings  operating  on  the  hardened  portion  of  the 
spindle.  Lubricant  for  the  pulleys  is  supplied  from  the  oil  chambers. 
The  friction  cones  are  engaged  with  the  pulleys  by  sliding  sleeve  F'  on 
levers  G'.  Adjustment  for  wear  is  secured  by  loosening  clamp  screw  H' 
and  turning  nut  /'.  At  J,  J,  Fig.  24,  is  shown  a  pair  of  screws  by  which 
the  clutch  sleeves  are  set  central  to  give  equal  pressure  on  the  two  pulleys. 

THE    SPIXDLE    REVERSE 

The  reversal  of  the  spindle  is  secured  through  the  action  of  spring 
plunger  K,  Fig.  24,  which,  upon  being  released,  throws  the  clutch  into 
in.stant  engagement  with  the  pulley  next  the  chuck.  To  run  forward 
the  clutch  is  engaged  with  the  other  pulley  by  cam  L,  which  is  operated 
by  clutch  M,  drawn  out  at  the  completion  of  one  revolution  b}'  lever 
N.  As  the  spindle  is  reversed  to  run  forward  the  plunger  spring  is  com- 
pressed by  the  action  of  the  cam,  the  plunger  being  held  in  place  by  a 
wide  portion  at  the  rear  end  of  the  lever  0.     The  carrier  D  shown  below 


40 


THE   BROWN   &   SHARPE  AUTOMATIC  SCREW   MACHINE 


REAR    ELKVATloX 


41 


42  THE   BROWN   &   SHARPE  AUTOMATIC   SCREW   MACHINE 

levers  A^  and  0  in  Figs.  21  and  23  is  provided  with  dogs  which  may  be 
adjusted  to  lift  the  levers  at  the  proper  time  for  reversing  the  spindle. 
Where  work  is  to  be  threaded  the  positive  clutch  P  serves  to  connect 
the  carrier  shaft  with  the  front-  or  cut-off  cam  shaft  Q.  This  clutch,  as 
already  stated,  is  disengaged  when  the  cross-slide  cams  are  to  be  changed 
and  need  not  be  connected  for  work  which  is  not  to  be  threaded.  The 
carrier  may  be  provided  with  two  or  more  sets  of  dogs  where  it  is  neces- 
sary both  to  thread  and  tap  the  work  or  to  cut  two  threads  on  it. 

OPERATION    OF    THE    SPRING    COLLET 

At  R,  Fig.  23,  is  shown  an  internally  tapered  sleeve  which  slides  over 
the  collet  and  closes  it  without  end  movement  of  the  latter,  thus  assuring 
accurate  stock  feeding  regardless  of  any  minute  variations  in  diameter. 
The  operation  of  the  sleeve  is  effected  by  the  chucking  tube  extend- 
ing through  the  spindle  to  the  rear  end,  where  it  is  controlled  by  the 
chuck  levers  S,  which  are  operated  by  sleeve  T,  which  sleeve  is  actuated 
by  a  lever  and  cam  U.  The  stock  is  also  fed  through  the  medium  of  this 
cam,  which  is  itself  actuated  through  spur  gears  V,  Fig.  24,  and  a  positive 
clutch  W  on  the  driving  shaft.  The  gears  and  clutch  are  plainly  shown 
on  the  shaft  in  Fig.  22.  A  lever  is  shown  under  this  clutch  in  Fig.  24, 
and  when  this  is  depressed  by  the  dog  on  carrier  E,  Figs.  21  and  23,  the 
clutch  is  engaged  and  makes  one  complete  revolution,  after  which  it  is 
again  disengaged  by  a  pin  in  the  lever  under  the  clutch  which  acts  upon 
the  cam  surface  of  the  clutch  and  causes  the  latter  to  return  to  its  former 
position. 

Adjustment  of  the  chuck  is  by  means  of  nut  A',  Fig.  23,  which  may 
be  turned  as  required  after  releasing  nut  Y.  The  collet  is  removed  by 
taking  off  the  cap  with  a  pin  wrench. 

THE    STOCK    FEED 

The  pulley  at  the  head  end  of  the  machine  for  driving  the  main  feed 
shaft  a,  Figs.  23  and  24,  is  engaged  by  a  clutch  actuated  by  hand  lever  b, 
which  thus  forms  a  means  of  controlling  the  feed  at  all  times. 

The  rear  end  of  the  stock-feed  tube  in  the  spindle  is  connected  by  a 
latch  c.  Fig.  25,  to  slide  d,  Fig.  24,  which  has  a  slot  in  which  is  a  sliding 
block  connecting  it  to  lever  e,  Figs.  24  and  25;  this  lever  is  operated  by 
cam  U  already  referred  to.  A  screw  and  crank  handle  G  -are  provided, 
as  indicated  in  Figs.  21,  22  and  24,  for  adjusting  the  sliding  block;  and 
lever  e  having  a  constant  stroke  the  length  of  feed  for  the  stock  is  varied 
by  changing  the  position  of  the  sliding  block.  The  length  of  feed  is 
shown  by  a  scale  which  is  secured  to  the  slide. 

By  lifting  latch  c,  Fig.  25,  the  feed  tube  may  be  withdrawn  and 
the  feeding  fingers  (which  are  threaded  left  hand)  may  be  changed.     It 


TURRET-SLIDE   OPERATION" 


43 


is,  of  course,  possible  to  feed  more  tlian  the  regular  capacity  of  the  ma- 
chine by  using  two  or  more  dogs  on  the  left  side  of  the  carrier  E,  Fig.  23, 
thus  operating  the  feed  mechanism  several  times. 


Fig.  25.  —  End  Elevation  Showing  Chuck  Operating 
Mechanism 

When  it  is  desired  to  stop  the  stock  feed,  as  in  adjusting  tools,  the  dog 
attached  to  lever  /.  Fig,  23,  can  be  turned  up,  thus  allowing  the  dogs  on 
the  carrier  E  beneath  to  pass  without  lifting  the  lever. 

THE    TURRET    SLIDE    AND    TURRET 

As  will  be  observed  upon  inspection  of  the  various  general  views, 
the  turret  is  mounted  at  the  side  of  the  turret  slide  and  rotates  in  the  ver- 
tical plane.  A  long  taper  shank  with  which  the  turret  is  provided  takes 
a  l)earing  in  the  turret  slide.  The  indexing  movement  is  accomplished 
by  means  of  a  hardened  steel  roll  in  disk  g,  Fig.  24,  engaging  with  grooves 
cut  radially  in  disk  h,  which  is  attached  to  the  rear  end  of  the  turret 
spindle.  The  turret  is  rotated  by  this  method  rapidly  and  starts  and 
stops  without  appreciable  shock.  The  taper  bolt  or  pin  which  locks  the 
turret  in  its  various  positions  is  shown  at  i,  Figs.  26  and  27.  The  lock- 
ing bolt  is  withdrawn  from  the  turret  by  cam  /. 

Tl'RRET-SLIDE    OPERATION 

The  forward  motion  of  the  turret  slide  for  feeding  the  cutting  tools 
along  the  work  is  imparted  by  a  bell-crank  lever  actuated  by  the  cam 
mounted  on  shaft  .4,  Figs.  22,  24.  and  28,  which  is  itself  driven  l)y  spur 
gears  from  the  shaft  and  worm  gear  k. 

While  the  turret  is  advancing  to  the  cut  and  returning  after  the  cut 
is  taken,  the  movement  of  the  turret  slide  and  the  revolving  of  the  turret 


44 


THE    BROWN    &    SHARPS   AUTOMATIC   SCREW   MACHINE 


are  controlled  independently  of  the  turret-slide  feed  cam  by  the  crank 
motion  /,  Fig.  27,  while  the  roll  carried  by  bell-crank  lever  m  is  passing 
from  the  highest  point  of  the  cam  for  the  turret-slide  feed  to  the  point 


Fig.  26.  —  End  View  of  Turret  Slide  Show- 
ing Locking  Pin  for  Turret 

where  the  next  cut  is  started.  The  rapid-motion  crank  /  is  operated  by 
gears  at  the  rear  of  the  machine  which  are  driven  by  positive  clutch  n, 
Fig,  24,  on  the  driving  shaft,  which  clutch  is  controlled  by  a  lever  and 
suitable  mechanism  for  giving  one  complete  revolution  in  similar  man- 
ner to  the  feed-mechanism  control  already  described.     As  crank  I  revolves, 


Mechanism  of  Turret  Slide 


spring  o  is  permitted  to  return  the  turret  slide  without  the  rack.  The 
turret  is  then  revolved  in  the  manner  described,  and  upon  the  crank  / 
coming  to  rest  after  it  has  completed  one  full  revolution,  the  machine 
is  ready  for  the  next  cutting  operation. 

THE    TWO    CROSS    SLIDES 

The  cross  slides  are  shown  clearly  in  Fig.  29.     They  are  operated  by 
cut-off  cam  shafts  Q,  Figs.  2.3  and  29,  driven  from  worm-wheel  shaft  k. 


THE   TWO   CROSS   SLIDES 


45 


Figs.  24  and  2.S,  through  the  medium  of  bevel  gears.     The  front  slide  is 
operated  directly  by  a  lever  with  gear  segment  formed  at  the  upper  end. 

m 


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Fig.  28.  —  Plan  Showing  Feed  Shaft,  Tripj)ing  Levers,  etc. 

The  rear  slide  has  an  intermediate  segment  gear  to  reverse  the  direction 
of  the  movement.  The  cams  for  the  two  slides  are  conveniently  placed 
side  by  side  on  their  shaft  (as  at  B  and  C,  Figs.  21  and  23)  and  the  por- 
tions which  impart  motion  to  the  slides  are  alike  in  both  cams.     The  racks 


Fig.  29.  —  Cross  Section  and  Cross-Slide  Mtrlianisni 

with  which  the  segments  mesh  extend  beyond  their  respective  slides  and 
their  projecting  ends  are  threaded  to  receive  nuts  for  adjusting  the  tools 


46 


THE   BROWN    &   SHARPE   AUTOMATIC   SCREW   MACHINE 


to  their  cuts.     In  addition  to  these  adjusting  nuts,  stop  screws  are  pro- 
vided at  the  rear  as  in  Fig.  29,  for  insuring  accuracy  in  forming  operations. 
Circular  tools  are  used  on  the  cross  slides  and  these  are  held  in  posi- 
tion on  blocks  pp  by  screws  qq  and  clamped  by  screws  r  r,  Fig.  29. 


DEFLECTOR 


In  Fig.  30  is  shown  a  deflector  which  is  operated  by  an  adjustable 
dog  on  carrier  E  and  separates  the  work  from  the  chips.     The  oil  pump 


Fig.  30.  —  Operation  of  Deflector 

is  driven  by  chains  from  the  main  pulley  and  is  not  stopped  when  the  feed 
clutch  is  disconnected;  thus  an  ample  supply  of  lubricant  on  the  work 
is  insured  at  all  times. 

TOOLS    AND    ATTACHMENTS 

Various  tools  used  on  this  machine  are  illustrated  in  Figs.  31  and  32, 
the  names  being  given  at  the  bottom  of  the  half-tones.  The  illustrations 
are,  in  most  cases,  self-explanatory.  No.  22  in  Fig.  32,  it  may  be  stated, 
is  an  adjustable  guide  applied  to  the  cross  slide  and  used  for  operating 
recessing  tool  20,  swing  tool  21,  and  taper  turner  23.  The  latter  has  two 
back  rests  and  one  cutting  tool  which  are  independently  adjustable,  and 
the  taper  given  the  work  is  determined  by  the  angle  on  the  guide  22. 
When  the  proper  taper  is  obtained,  the  tool  and  the  back  rests  are  with- 
drawn radially  from  the  work,  thus  preventing  tool  marks  on  the  finished 
piece. 

The  construction  of  the  releasing  die  holder  is  shown  in  Fig.  33.  A 
is  the  driving  pin  and,  when  it  is  pulled  out  of  the  plate  B,  the  die  holder 


TOOLS    AM)    ATTACHMKXTS 


1.    IVihI  Chuck. 

4.    Box  Tool  with  Ccntor 

Drill. 
7.    Adju.stahle  Hollow  Mill 

(Finishing). 

10.    Die  Holder  (Releasing).     14.    Klo;ttin<r  Holder. 
V.i.    Drill  Holder. 


■J.    Spring  ("ollct. 

o.    Pointing  Tool. 

S.    Adjustalile  Hollow  Mill 

( Roughing). 
11.    Tap  Hold(T. 


4.    Box  Tool. 

G.    Centering  and  Facing 
Tool. 

9.    Die  Holder. 
12.    Tap  Holder  (Releasing), 
lo.    Back  Rest  for  Turret. 


Fig.  31.  —  Brown  t!i:  Sharpe  Automatic  Screw  Machine  Tools 


48 


THE  BROWN   &  SHARPE  AUTOMATIC  SCREW   MACHINE 


16.   Angular  Cutting-off  Tool.  17.    Nurl  Holder  for  Turret.     IS.  Nurl    Holder   for   Cross 

19.  Nurl  Holder  for  Cro.s.s  Slide.  20.    Recessing  Tool.                               Slide. 

22.  Adjustable  Guide  used  with  21.    Swing  Tool.                          23.  Taper  Turning  Tool. 

Tools  20,  21,  23.  24.  Tool    Post    for    Square 
25.   Cutting-off   Tool    Post                                                                         Tools. 

(High).  26.  Cutting-off  Tool  Post 

(Low). 

Fig.  32.  —  Brown  tt  Sharpe  Automatic  Screw  Machine  Tools 


TOOLS  AND  ATTACHMENTS 


49 


releases  and,  when  the  spindle  is  reversed,  the  ball  C  drives  the  die  off. 
One  ball  recess  is  for  rio;ht-hand  threads  and  the  other  for  left-hand 
threads.  With  this  die  holder  the  turret  slide  can  move  back  some  dis- 
tance after  the  holder  is  released  and  still,  as  soon  as  the  spindle  is 
reversed,  the  die  will  be  backed  off  the  thread. 


Fi(i.  .33.  —  Releasino;  Die  Holder 

No  circular  forming  tools  arc  included  in  the  groups  in  Figs.  31  and 
32,  but  in  Fig.  34  two  circular  tools  and  their  holders  are  plainly  shown. 
This  illustration  also  represents  clearly  the  tap  and  die  revolving  attach- 
ment which  rotates  the  tap  or  die  in  the  same  direction  as  the  spindle, 
but  at  one-half  the  spindle  speed.  It  is  of  service  where  the  work  requires 
no  other  slow  movement  except  that  for  threading  and  enables  the  spindle 
to  be  run  at  its  maximum  speed  for  satisfactory  production  of  the  work, 
while  the  tap  or  die  is  revolved  at  a  suitable  speed  for  tliroading. 


lie.  34.  -    Tup  and  Die  Revolving  Attaeliiiient 

Fig.  3.5  shows  the  .screw-slotting  attachment  which  takes  the  screws 
as  they  are  left  by  the  machine  and  slots  them  automatically.  The  saw 
is  mounted  on  a  slide  and  diiven  by  a  round  belt  fioin  the  countei'shaft. 
It  can  be  adjusted  for  depth  of  cut  by  a  screw  at  tlie  back  of  the  slide. 


50 


THE  BROWN   &  SHARPE  AUTOMATIC  SCREW  MACHINE 


The  screw  to  be  slotted  is  held  in  a  bushing  carried  in  a  floating  holder 
mounted  in  a  swinging  arm  which  can  be  adjusted  radially  by  a  screw 
and  nut  on  the  rotating  lever.  The  device  is  operated  by  cams  that  are 
mounted  as  intlicated  on  the  front  shaft  of  the  machine.  The  forward 
and  upward  movements  of  the  arm  are  positive  and  the  return  movements 
are  controlled  by  springs. 


Fig.  35.  —  Screw-Slotting  Attachment 

Another  attachment  (not  shown)  is  for  running  a  drill  at  high  speed 
where  small  holes  are  recjuired  in  the  work.  This  attachment  is  also 
driven  by  a  round  belt  from  the  counter. 

COUNTERSHAFT    ARRANGEMENT 

Figs.  36  and  37  show  the  overhead  works  for  the  No.  00  automatic. 
As  will  be  observed,  there  are  two  countershafts;  the  first  one  having  8- 
inch  fast  and  loose  pulleys  taking  3-inch  belts.  This  shaft  should  run  at 
about  450  turns  per  minute.  The  second  countershaft  is  driven  by  a 
six-step  cone  pulley  and  has  a  drum  14f  inches  diameter,  and  two  smaller 
pulleys  10|  and  5^  inch  diameter  respectively  for  operating  the  spindle 
pulleys. 

A  double  pulley  running  freely  on  the  end  of  the  shaft  serves  as  an 
intermediate  between  the  first  counter  and  the  feed-driving  pulley  on 
the  machine.  Thus  a  constant  rate  of  speed  is  provided  for  the  feed 
mechanism  regardless  of  the  spindle  speed. 


SIZES  OF  MACHINES 


51 


Fig.  36.  —  Plan  cf  Overhead  Works  for  Brown 
&  Sliarpe  No.  00  Automatic  Screw  Machine 


^(i'l^njZZZr-^^^M 


Fig.  37.  —  Front  and  End  Elevations  of  Overhead  Work.s  for  Brown  c^  Sharpc  No.  tK) 

Auioinatic  Screw  Machine 

SIZES    OF    M.\CHIXES 

The  chuck  aiul  turning  capacityof  the  No.  00  machme,ns  ah-eady stated, 
is  IS  by  l\  inch,  the  maximum  length  that  can  be  fed  being  2  inches. 
The  No.  0  machine  receives  stock  up  to  V  inch  in  the  chuck,  turns  lengths 
up  to  1^  inches  and  has  a  maximum  feeding  movement  of  3  inches.  Tiie 
No.  2  machine  handles  material  up  to  |-inch  diameter,  turns  lengths  up 
to  2\  inches  and  feeds  any  length  up  to  4  inches. 


CHAPTER   IV 

Laying  Out  Brown  &  Sharpe  Screw  Machine  Cams 

This  chapter  on  camming,  prepared  by  F.  E.  Anthony,  of  Providence, 
R.  I.,  gives  a  practical  idea  of  the  method  employed  in  laying  out  the 
cams  for  the  Brown  &  Sharpe  automatic  screw  machine.  The  example 
taken  is  a  simple  screw,  but  the  laying  out  of  the  cams  and  the  methods 
employed  are  practically  the  same  for  a  more  complicated  piece,  excepting 
that  the  lobes  of  the  cams  would  necessarily  have  to  be  designed  to  suit 
the  various  operations  on  more  complicated  work. 

order  of  operations 

Assuming  that  a  screw  as  shown  in  Fig.  38  is  to  be  made  from  com- 
mon yellow  brass  and  the  requirements  are  such  that  it  is  necessary  to 
take  roughing  and  finishing  cuts  to  produce  the  desired  blank  size  before 
threading,  the  following  order  of  operations  would  be  selected:  rough 
turn  with  hollow  mill;  index  turret;  finish  turn  with  box  tool;  index  tur- 
ret; thread;  cut-off  screw;  feed  stock  to  stop;  index  turret. 

The  facing  of  the  under  side  and  the  removing  of  the  bur  on  the  outer 
diameter  of  the  head,  as  well  as  the  indexing  of  the  turret  three  times 
to  bring  the  stop  into  position  for  feeding  the  stock  for  the  next  blank, 
are  not  considered  in  the  above  operations,  as  usually  these  operations 
can  be  performed  during  the  time  required  for  parting  the  screw  from 
the  bar. 

The  spindle  speed,  length  of  cuts,  feed  per  revolution  of  spindle 
for  the  various  cuts,  the  time  consumed  by  the  idle  movements,  such  as 
feeding  the  stock,  indexing  the  turret  and  reversing  the  spindle,  also  the 
clearance  between  the  turret  and  cross-slide  tools,  are  taken  into  con- 
sideration to  determine  the  total  number  of  revolutions  of  spindle  required 
for  completing  the  screw.  The  fastest  spindle  speed  for  the  machine, 
which  is  2400,  can  be  used  for  brass. 

determining  the  number  of  spindle  revolutions 

To  determine  the  number  of  revolutions  of  the  spindle  required  for 
the  various  cuts,  divide  the  length  of  cut  by  the  feed  or  advance  of  the 
tool  per  revolution  of  the  spindle.  Calculating  on  a  feed  of  0.012  inch 
for  roughing,  which  cut  is  1  inch  long,  83  revolutions  and  a  fraction  of 

52 


SPINDLE   REVOLUTIONS    DURINO   CROSS-SLIDE   MOVEMENTS       53 

a  revolution  will  be  required.  As  it  is  not  practicable  to  consider  frac- 
tions of  revolutions,  the  roughing  cut  will  be  given  84  revolutions.  After 
the  roughing  cut,  the  turret  is  indexed  to  bring  the  finishing  tool  into 
position.  The  mechanism  that  rotates  the  turret  maintains  a  constant 
speed,  and  the  indexing  of  the  turret,  to  bring  another  tool  to  the  cutting 
point,  requires  one-half  second  in  all  cases.  With  the  spindle  running 
2400  revolutions  per  minute,  each  change  consumes  20  revolutions.  It 
is  an  advantage,  however,  to  allow  extra  revolutions  for  the  operation 
to  facilitate  adjusting  the  dogs  that  control  the  mechanism;  allowing  22 
revolutions  for  the  change  will  give  the  desired  result. 

For  the  finishing  cut,  which  is  1  inch  long,  and  calculating  a  feed  of 
0.012  inch  per  revolution,  84  revolutions  will  have  to  be  allowed  as  for 
roughing. 

The  pitch  of  the  thread  on  the  screw  being  60  per  inch,  the  number 
of  revolutions  required  for  running  the  die  on  the  screw  (which  has  a 
thread  i  inch  long)  will  be  one-half  of  60,  or  30,  actual  i-evolutions.  To 
this  amount  should  be  added  extra  revolutions  for  clearance;  allowing 
33  revolutions  for  running  the  die  on  to  the  screw  and  the  same  num- 
ber for  backing  the  die  off  will  give  a  total  of  66  revolutions  for  threading. 

SPINDLE     REVOLUTIONS    REQUIRED     DURING     CROSS-SLIDE     MOVEMENTS 

A  certain  amount  of  the  cam  circle  nmst  be  allowed  between  the 
threading  and  cutting-off  operations,  so  that  the  cross-slide  tools  will 
not  begin  to  advance  to  the  cutting  point  until  the  die  holder  has  dropped 
back  beyond  the  interfering  point.  The  drop  for  each  cross  slide  is  1 
inch,  giving  a  distance  of  2  inches  from  edge  to  edge  of  the  cross-slide 
tools,  with  the  slides  in  the  backward  position. 

The  die-holder  cap  with  adjusting  screws  requires  approximately 
Ih  inches  space  to  pass  through;  as  there  are  2  inches  between  the  cross- 
slide  tools,  should  these  tools  begin  to  advance  to  the  cutting  point  as  soon 
as  the  die  reaches  the  end  of  the  screw  (when  backing  off),  there  would 
be  a  trifle  more  clearance  than  actually  required. 

Consulting  the  templet  shown  in  Fig.  39.  it  will  be  noted  that  o  hun- 
dredths of  the  cam  circle  ai-e  taken  up  in  advancing  the  cross  slide  from 
its  backward  position  (which  is  detei-mined  by  the  low  portion  of  the  cam) 
to  the  point  where  the  tool  commences  the  cut.  The  revolutions  of  the 
spindle  during  this  clearance  can  be  determined  after  finding  the  total 
revolutions  required  for  the  different  operations  antl  idle  movement. 

The  cutting-off  tool,  as  shown  in  Fig.  38,  is  arrangetl  with  a  parting 
blade  that  has  a  23-degree  angle  on  the  cutting  edge;  this  is  for  the  purpose 
of  making  the  parting  close  to  the  head  of  the  screw,  to  avoid  leaving 
a  large  teat  on  the  piece  when  dropped. 

Using  an  angular  blade,  it  is  necessary  to  allow  extra  travel  so  that 


54        LAYING    OUT   BROWN    &   SHARPE   SCREW   MACHINE   CAMS 


W     I 


-1 

1 

i 

i^ 

=^ 

8 

INDEXING    AND   STOCK-FEEDING    ALLOWANCE  55 

the  low  point  of  the  angle  can  be  carried  a  trifle  by  the  center  of  the  spindle 
to  insure  removing  the  teat  on  the  bar,  which  is  termed  "by  travel." 
Add  to  the  radius  (0.125  inch)  of  the  bar  used  0.019  inch,  the  amount  of 
"by  travel"  required  for  the  cutting-off  tool  plus  0.003  inch  clearance 
to  allow  for  variations  in  material,  and  we  have  a  total  of  0.147  inch  ti-avel 
for  the  cutting-off  tool;  considering  a  feed  or  advance  of  0.0015  inch  per 
revolution,  api)roximately  97  revolutions  will  be  required  for  cutting 
off. 

The  facing  of  the  under  side  of  the  head  (the  tool  for  which  travels 
from  \  inch  diameter  of  stock  to  I  diameter  of  finished  size)  requires  a 
travel  of  0.067  inch,  including  clearance  to  allow  for  variation  in  ma- 
terial; this  cut  carried  at  a  feed  of  0.0016  inch  will  require  approximately 
42  revolutions.  As  this  cut  can  begin  at  the  same  time  as  the  cutting- 
off  operation  and  will  be  completed  by  the  time  the  screw  is  partially 
cut  off,  the  revolutions  recjuired  need  not  be  considered  when  determin- 
ing the  total  number. 

INDEXING    AND    STOCK-FEEDING    ALLOAVANCE 

As  there  are  but  four  turret  tools  used  in  making  the  screwy  it  will 
be  necessary  to  index  the  turret  three  times  after  the  threading  operation 
to  bring  the  stop  into  position  for  feeding  the  stock  for  the  following 
screw.  The  97  revolutions  allowed  for  cutting  off  will  give  ample  time 
for  these  changes. 

An  allowance  of  22  revolutions  must  be  added  for  feeding  the  stock 
to  the  stop  after  cutting  off  and  indexing  the  turret,  to  bring  the  rough- 
ing tool  into  position  for  the  following  screw. 

The  following  table  shows  the  total  number  of  revolutions  recjuired 
for  actual  operations: 

Revolutions. 

Roughing  cut 84 

Index  turret 22 

Finishing  cut  ...    84 

Index  turret 22 

Threading 66 

Clearance  

Cutting  off 97 

(Index  turret  three  times;   face  under  side  of  head.) 

Feed  stock 22 

Index  turret 22 

419 

As  5  hundredths  of  the  cam  circle  must  be  allowed  for  clearance  be- 
tween the  die  holder  and  cross-slide  tools,  the  above  total  of  419  revolu- 
tions represents  95  hundredths  of  the  cam  circle.  Dividing  419  by  95. 
the  quotient,  4.41  (the  number  of  revolutions  in  1  hundredth),  multiplied 


56        LAYING   OUT   BROWN    &    SHARPE   SCREW    MACHINE   CAMS 

by  100  gives  a  total  of  441  revolutions  of  the  spindle  to  complete  the 
screw. 

SELECTING    CHANGE    GEARS 

With  each  machine  a  number  of  change  gears  are  furnished  to  allow 
the  cam-shaft  speeds  to  be  varied  from  3  to  30  seconds  per  revolution. 
These  gears  allow  variations  of  one  second  to  be  made.  As  the  spindle 
makes  40  revolutions  per  second,  selecting  a  train  of  gearing  from  the  gear 
table  (see  Table  12.  page  61)  accompanying  the  machine,  that  will  give 
a  revolution  of  the  cam  shaft  in  11  seconds,  the  spindle  will  make  440 
revolutions  to  one  of  the  cam  shaft.  It  will,  therefore,  be  necessary 
to  take  away  a  revolution  from  one  of  the  operations,  the  total  being  441. 
Allowing  96  revolutions  for  cutting  off,  instead  of  97,  as  previously  calcu- 
lated upon,  will  not  make  any  material  difference  to  the  feed  for  this  cut. 

DIVISION    OF   THE    CAM    CIRCLE 

As  it  is  not  convenient  to  divide  the  cam  blanks  into  various  num- 
bers of  parts  equal  to  the  number  of  revolutions  required  for  making 
different  pieces,  it  is  the  general  practice  to  divide  the  cam  circle  into 
100  equal  parts,  as  shown  in  Fig.  40.  The  number  of  hundredths  for 
the  lobes  and  spaces  on  the  cams  is  obtained  by  dividing  the  number  of 
revolutions  for  each  operation  by  the  total  number,  taking  the  nearest 
decimal  with  two  places.  For  example:  The  number  of  revolutions  for 
the  roughing  cut  is  84;  dividing  84  by  440,  the  result,  0.19,  is  the  number 
of  hundredths  of  the  cam  circle  required  for  the  first  cut.  Reducing  the 
remainder  of  the  operations  in  the  same  manner  the  cam  circle  is  divided 
as  follows:  u     i  .•         v    ^   a.i. 

Revolutions.      Hundredths. 

Rough  turn 84  19 

Index  turret 22  5 

Finish  turn 84  19 

Index  turret 22  5 

Thread 66  15 

Clearance 22  5 

Cut  off 96  22 

Feed  stock  to  stop 22  5 

Index  turret 22  5 

440  loo 

THE    TURRET    AND    CROSS-SLIDE    CAMS 

Commencing  at  the  line  opposite  the  |-inch  hole  in  the  cam  blank, 
as  shown  in  Fig.  38,  the  turret-slide  cam  is  divided  as  follows: 

0  to  19,  lobe  for  roughing  cut ; 
19  to  24,  space  for  indexing  turret; 
24  to  43,  lobe  for  finishing  cut; 
43  to  48,  space  for  indexing  turret; 


THE    LAYOUT  57 

48  to  63,  lobe  for  threading; 

63  to  90,  reduced  to  diameter  (2^  inches)  of  cam  carrier,  allowing 
turret  to  dwell  in  rear  position  during  the  time  taken  up 
for  clearance  and  the  cutting-off  and  facing  operation; 

90  to  95,  lobe  for  feeding  stock; 

95  to  0,  space  for  indexing  turret. 
A  clearance  of  5  hundredths  has  been  calculated  on  after  threading 
to  avoid  interference  of  the  cross-slide  tools  with  tiie  die  holder,  in  which 
case  the  cross-slide  cam  for  cutting  off  will  commence  at  68  and  extend 
to  90.  The  parting  of  the  piece  from  the  bar  will  occur  before  the  com- 
plete portion  of  the  lobe  has  passed  the  roll  on  the  cross-slide  lever,  due 
to  the  extra  amount  of  throw  on  the  cam  necessary  for  removing  the 
teat  on  the  bar  which  has  previously  been  termed  "by  travel,"  in  which 
case  the  stop  for  feeding  the  stock  can  be  in  position  as  soon  as  the  cutting- 
off  tool  commences  to  drop  back  after  cutting  off.  The  travel  of  the 
facing  tool,  which  commences  at  \  diameter  and  is  carried  forward  to  ^ 
diameter,  will  be  ai)proximately  0.067  inch,  including  clearance;  advan- 
cing the  tool  at  0.0016  inch  per  revolution,  42  revolutions  will  be  required. 
To  this  number  are  added  2  revolutions  for  dwell  of  the  tool  at  the  finish- 
ing point,  making  a  total  of  44  revolutions,  which  takes  u{)  10  hundredths 
of  the  cam  circle.  As  2  revolutions  for  dwell  will  require  +  hundredth, 
the  throw  of  0.067  inch  will  take  9^  hundredths  of  cam  surface. 

The  facing  operation  commences  at  the  same  time  as  the  cutting  off; 
consequently  the  spacing  of  the  front-slide  cam  will  be  from  68  to  772- 
for  advance  of  tool,  77^  to  78  for  dwell. 

The  hight  of  the  various  cam  lobes  is  determined  by  the  lengths  of  the 
tools  to  be  used.  The  face  of  the  turret  is  approximately  1^-  inches  fi-om 
the  face  of  the  chuck,  with  the  turret-slide  lever  on  a  cam  portion  4^ 
inches  diameter. 

THE    LAYOUT 

On  the  cam  layout  sheet.  Fig.  38.  three  perpendicular,  parallel  lines, 
approximately  1  inch  long,  should  be  drawn,  with  a  distance  of  1;^-  inches 
between  the  first  and  second,  and  11,  inches  between  the  second  and 
third  lines.  The  first  line  represents  the  face  of  the  chuck;  the  second, 
the  face  of  the  turret  with  the  lever  on  a  cam  41  inches  diametei-;  and  the 
third,  the  face  of  the  turret  with  the  slide  in  the  rear  position.  A  line 
drawn  at  right  angles  through  the  center  of  these  lines  represents  the  cen- 
ter of  the  spindle.  The  cross-slide  tools  and  sample  should  be  drawn  to 
scale  close  to  the  chuck  line.  The  line  repre.senting  the  center  of  the 
spindle  is  necessarily  the  center  of  the  piece  to  be  made.  The  roughing 
and  finishing  cuts  are  carried  close  to  the  under  side  of  the  head  of  the 
screw.  The  hollow  mill  and  the  head  portion  of  its  holder,  which  ex- 
tends beyond  the  face  of  the  turret,  is  If  inches  long,  as  shown  in  Fig.  41; 


58 


LAYING   OUT   BROWN    A-    SHARPE   SCREW   MACHINE   CAMS 


as  the  under  side  of  the  head  is  approximately  1^4  inches  from  the  line, 
representing  the  face  of  the  turret  in  the  forward  position  on  a  4^-inch 
cam  diameter,  it  will  be  necessary  to  arrange  for  the  high  point  on  the 
lobe  to  stop  at  least  ^^2  inch  below  the  4^-inch  circle  on  the  layout  sheet, 
so  that  the  cut  will  not  be  carried  forward  to  such  a  point  that  the  proper 


Fig.  41.  —  Diagram  of  Turret  and  Tools 

thickness  of  head  cannot  be  obtained.  An  extra  thirty-second  of  an  inch 
should  be  allowed  to  facilitate  adjusting  the  tool,  in  which  case  the  high 
point  of  the  roughing  lobe  should  stop  j\  inch  below  the  4^-inch  circle; 
as  the  rise  on  that  lobe  is  1  inch  (the  length  of  the  cut),  the  low  point 
will  be  lyV  inches  below  the  4^-inch  circle. 


THE    TURRET-SLIDE    CAM    LOBES 

From  the  zero  line  to  19  hundredths  of  the  cam  circle,  construct  an 
increase  curve,  with  a  rise  of  1  inch  for  the  roughing  cut.  The  method  of 
laying  out  the  increase  curve,  approximately,  is  shown  in  Fig.  38.  With 
a  templet  as  shown  in  Fig.  39  draw  the  line  of  drop,  beginning  at  19  hun- 


THE   CROSS-SLIDE   CAM   LOBES  59 

dredths,  and  draw  an  arc  equal  to  the  radius  {{  incli)  of  the  turret-sh'de 
lever  roll,  tangent  to  the  drop  line,  with  the  low  point  of  the  arc  about  xV 
inch  below  the  starting  point  of  the  following  lobe.  The  lobe  for  the 
finishing  cut  is  a  duplicate  of  the  roughing. 

In  constructing  the  threading  lobes,  it  is  the  usual  practice  to  allow 
the  die  head,  which  is  arranged  to  slide  on  the  holder,  to  draw  away  from 
the  turret  to  prevent  crowding  the  die  on  to  the  work. 

As  33  revolutions  are  allowed  for  running  the  die  on  to  the  screw, 
the  advance  of  the  die  would  be  §g  (0.537  inch).  From  this,  deduct  0.060 
inch  to  allow  the  die  to  draw  away  from  the  turret.  The  result,  0.467 
inch,  is  the  rise  for  the  lobe,  and  the  drop  for  backing  the  die  off  of  the 
screw  must  necessarily  be  the  same. 

When  determining  the  hight  of  the  lobe,  the  amount  of  "pull  out" 
allowed  for  the  die  must  be  taken  into  consideration. 

The  length  of  the  die-holder  head,  as  shown  in  Fig.  41,  is  l./jj  inches 
plus  0.060  inch  allowed  for  "pull  out."  The  result,  which  is  approxi- 
mately 1^^  inches,  is  the  total  length  of  holder  to  be  considered. 

The  threading  begins  at  48  hundredths  and  requires  15  hundredths 
of  cam  surface.  The  rise  for  following  the  die  on  the  screw  would  be 
0.467  inch  (7^  hundredths).  Locating  the  high  point  of  the  lobe  at 
55^  hundredths,  the  length  of  the  holder  plus  ^V  inch  for  clearance  makes 
it  nece.ssary  to  cut  the  high  point  ^f  inch  below  the  4^-inch  circle. 

Construct  the  increase  curve  for  the  drop  and  rise  in  the  same  man- 
ner as  shown  in  Fig.  38  for  the  roughing  cut. 

The  die  will  have  backed  ofif  the  screw  at  63  hundredths  and  the  por- 
tion of  cam  surface  from  this  point  to  the  starting  point  of  the  stop  lobe 
should  be  cut  down  1^  inches  from  the  4i-inch  circle  to  allow  the  turret 
to  remain  in  the  rear  po.sition  during  the  cutting  off  and  facing  operations. 
Allowance  should  be  made  for  the  drop  from  the  point  on  the  threading 
lobe  ami  the  rise  for  the  .stop  lobe,  using  the  templet,  Fig.  39,  for  con.struct- 
ing  the  lines. 

THE    CROSS-SLIDE    CAM    LOBES 

The  cross-slide  cam  blanks  are  4A  inx'hes  diameter.  It  is  not  nece.ssary 
to  cut  the  high  point  of  the  lobes  on  the  cams  below  this  diameter  when 
using  forming  and  cutting-off  tools,  as  the  .slides  are  arranged  with  suit- 
able adjustment  for  producing  any  diameter  within  the  capacity  of  the 
machine. 

Tne  rise  and  drop  on  the  cross-.slide  cams  are  constructed  from  the 
templet.  Fig.  39,  and  should  be  spaced  in  the  same  manner  as  the  turret- 
slide  cam,  using  the  locating-pin  hole  for  the  zero  line,  in  order  to  time 
the  cams  properly  when  placed  in  the  machine. 

The  cutting  off  commences  at  68  and  is  completed  at  90  hundredths; 
the  facing  is  from  68  to  78  hundredths. 


60        LAYING   OUT   BROWN   &   SHARPE   SCREW  MACHINE   CAMS 
STOCK    STOP,    SPIXDLE    REVERSE,    ETC. 

The  stop  lobe  from  90  to  95  hundredths  is  without  advance  to  produce 
a  dwell  of  turret  slide  while  feeding  the  stock.  From  95  hundredths  to 
zero,  a  drop  necessary  to  bring  the  turret-slide  lever  roll  yV  ^i^ch  below 
the  starting-point  for  the  roughing  cut  is  constructed. 

The  reversing  of  the  spindle  does  not  consume  time  enough  to  make 
it  necessar}'  to  allow  on  the  threading  lobe  for  this  change.  The  revers- 
ing of  the  spindle  from  backward  to  forward  after  cutting  off  can  be 
carried  on  during  the  operation  of  feeding  the  stock  or  revolving  the 
turret. 


BROWN    &    SHARPE    C.\M    TABLES 


61 


No.  00  AUTOMATIC  SCREW  MACHINE. 
Table  for  Laying:  Out  Cams. 


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The  number  of  hundredths  given  is  always  sufficient  for 
usually  best  to  add  1-JOO  for  revolving  the 

Table  12.  —  For  Laying  Out  Cams  for  Brown  A:   Shari>e 

Machine. 


feeding 
Turret. 


stock,  but  it  is 


No.  OU  Automatic  Screw 


62        LAYING   OUT   BROWN   &   SHARPE   SCREW   MACHINE   CAMS 


No.  0  AUTOMATIC  SCREW  MACHINE 
Table  for  Laying-  Out  Cams. 


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Table  13. 


For  Laying  Out  Cams  for  Brown  &  Sharpe  No.  0  Automatic  Screw 
Machine. 


BROWN    &    SHARPE    CAM    TABLES 


63 


No.  2  AUTOMATIC  SCREW  MACHINE. 
Table  for  Laying  Out  Cams. 


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LU 

CC 

u. 

0 

cc 
ai 
ca 

:d 
z 

24 

30 

36 

45  5 

5  68 

84 

104 

128 

158 

195 

240 

13 

2769 

2400 

80 

32 

72 

78 

9 

26 

32 

39 

49  6 

0  74 

91 

112 

139 

171 

211 

260 

M 

2571 

2300 

So 

32 

60 

70 

8 

2S 

35 

42 

52  6 

5  So 

98 

121 

149 

184 

227 

280 

i6 

2250 

2000 

So 

32 

60 

80 

7 

32 

39 

49 

60  7 

4  91 

112 

138 

171 

210 

259 

320 

i8 

2COO 

iSoo 

80 

32 

43 

72 

6 

36 

44 

55 

67  8 

4  103 

126 

156 

192 

237 

292 

360 

20 

1800 

1600 

So 

32 

48 

80 

5 

40  49 

61 

75  9 

2  114  140 

173 

213 

263 

324 

400 

22 

1636 

1450 

80 

32 

42 

77 

5 

44  54 

67 

82  IC 

2  125  154 

190 

235 

289 

357 

440 

24 

1500 

1350 

80 

32 

40 

80 

5 

4SI  59 

73 

90  II 

I  137  16S 

208 

256 

316 

389 

480 

26 

1384 

1250 

80 

32 

36 

78 

4 

5= 

64 

79 

97ii^ 

0  14S  1S2 

225 

277 

342 

422 

520 

28 

I2S5 

^50 

80 

32 

36 

S4 

4 

56 

69 

85 

I05J12 

9  160 

196 

242 

299 

368 

454 

560 

ao 

1200 

1050 

60 

60 

So 

80 

4 

60 

74  91 

11213 

8  T71 

210 

259 

320 

394 

4S6 

600 

35 

1028 

925 

60 

60 

72 

84 

3 

70 

87I106 

.3.!ie 

2  199 

246 

303 

373 

460 

568 

700 

40 

900 

800 

60 

60 

54 

72 

3 

8oj  99121I150J1S 

5  228 

281 

346 

427 

526 

649 

800 

45 

800 

700 

60 

60 

48 

72 

3 

90|i  1 1 

136J1692C 

S  256 

316 

389 

480 

592 

730 

900 

50 

720 

625 

60 

60 

48 

80 

3 

loo'i: 

IIOI^ 

4 

15218723 

I  285 

351 

432 

533 

657 

811 

1000 

55 

654 

575 

60 

60 

42 

77 

3 

6i67|2o6;2  5 

4  313 

386 

476 

587I  723 

892 

1100 

60 

600 

525 

40 

80 

60 

60 

3 

I20  14bilS2?25!27 

7  342 

421 

519 

640 

7S9 

973 

1200 

70 

514 

450 

40 

So 

60 

70 

3 

l4ojl73'2i2 

160198,243 

p62'32 

3  399 

491 

605 

747 

920 

11351400 

80 

450 

400 

40 

So 

54 

72 

3 

300,3c 

9  456 

56. 

692 

S53 

1052 

1297,1600 

90 

400 

350 

40 

So 

48 

72 

3 

i8o|222273^374i 

5  513 

631 

778 

960 

1183 

1459J1800 

100 

360 

300 

40 

80 

48 

80 

3 

200,2471033754c 

2  570 

702 

861 

1067 

1315 

1622 

2000 

110 

327 

290 

40 

So 

42 

77 

3 

2201272334^12  5c 

)8  627 

772 

951 

1173I1446I17S4 

2200 

120 

300 

270 

40 

So 

40 

So 

3 

2401296  364'^!  50  55 

4  684 

842 

103S12S0  157SI1946 

2400 

135 

266 

240 

36 

72 

40 

90 

3 

2  70J33409;5<^^(^; 

3  769  947Jii68ii440,i775  2iS9 

2700 

150 

240 

210 

36 

80 

40 

90 

3 

300i370  4  55'562J6c 

)2  855  i052;i297;i6oo!i972  2432 

3000 

I6S 

218 

190 

36 

77 

35 

90 

3 

33o!407  50o^icJ7c 

2  9401158 

i427li76o;2i70  2675 

3300 

180 

200 

180 

36 

34 

35 

90 

3 

360^144 

546,67^8311102^1263 

15571192012367,2919 

3600 

Table  14.  —  For  Laying  Out  Cams  for  Brown  «S:  ^harpc  No.  2  Automatic  Screw 

Machine. 


CHAPTER   V 

The  Brown  &  Sharpe  Automatic  Screw  Machine   with  Constant- 
Speed  Drive 

The  Brown  &  Sharpe,  No.  2  G,  automatic  as  equipped  with  constant- 
speed  (h-ive  is  illustrated  in  Figs.  42,  43,  and  44.     The  general  form  of 


Fig.  42.  —  Brown  <t   Sharpe  Automatic  .Screw  Machine  with  Constant-Speed  Drive 

the  machine  itself  is  practically  unchanged  from  the  design  illustrated  in 
Chapter  III,  the  new  features  being  detailed  in  Fig.  43. 

64 


CONSTANT    SPEED    DRIVE 


65 


A  friction  clutcli  is  located  in  tlic  driving  pulley  .1,  allowing  the  ma- 
chine to  be  driven  direct  from  the  main  line.  Any  standard  constant- 
speed  motor  can  be  mounted  upon  the  machine. 

The  spindle  is  driven  by  silent-running  chains.  Variations  of  the 
spindle  speeds  are  obtained  by  means  of  change  gears  and  friction 
clutches,  each  pair  of  change  gears  giving  two  spindle  speeds  one  slow 
and  one  fast,  automatically  changed  by  the  friction  clutches.  There  is 
also  a  friction  clutch  located  on  the  spindle  for  reversing,  so  that  with 
the  whole  combination  it  is  possible  to  obtain  twelve  forward  changes 
and  twelve  backward  changes  of  speed  for  the  spindle. 


Fig.  4.3.  —  Details  of  the  Constant-Speed  Drive 


The  feed-driving  mechanism  is  positively  connected  with  the  spindle- 
driving  mechanism.  The  i)()wer  is  taken  by  the  driving  pulley  .1.  to 
which  the  sliding  gear  />'  is  connected  by  a  friction  clutch.  Hy  means  of 
this  friction  clutch  the  machine  is  started  or  stopped,  and  there  is.  in 
addition,  indepemlent  means  provided  for  starting  and  stopping  the  feed 
when  desired. 

The  slitling  gear  B  through  gear  C  drives  back  shaft  D,  which  in  turn 
drives  the  clutch  shaft  G  through  the  change  gears  E  and  F.  Keyed  to 
the  shaft  G  is  the  friction  body  with  faces  H  and  /,  and  mounted  loosely 


66 


THP:   brown    &   SHARPE   AUTOMATIC   SCREW   MACHINE 


on  shaft  G  is  the  gear  ./  on  one  side  of  the  friction  body,  and  on  the  other 
side  of  the  body  the  gear  K  and  chain  sprocket  L,  both  of  which  are 
fastened  to  the  friction  back  M. 

Mounted  loosely  on  shaft  D  is  a  quill  on  which  are  the  gears  0  and  B 
and  the  sprocket  P^.  When  the  clutch  face  /  engages  the  friction  back 
M,  the  spindle  is  driven  back  at  a  slow  speed  through  the  sprocket  L 
and  the  chain  and  sprocket  A^  and  the  spindle  is  driven  forward  at  a  slow 
speed  through  gears  K  and  0,  the  sprocket  P,  and  chain  and  sprocket  Q. 
When  the  clutch  face  H  engages  the  gear  J  the  spindle  is  driven  forward 
at  a  fast  speed  through  gear  B,  the  sprocket  P,  and  the  chain  and  sprocket 
Q,  and  is  driven  backward  at  a  fast  speed  through  gears  R,  0,  and  K,  the 
sprocket  L  and  chain  and  sprocket  A^. 


Fig.  44.  —  Details  of  Clutch 

The  direction  of  the  spindle  rotation  depends  upon  whether  the  clutch 
body  on  the  spindle  is  engaged  with  sprocket  A^  or  sprocket  Q,  both  of 
which  are  loose  on  the  spindle  and  are  provided  with  roller  bearings.  All 
bearings  in  the  driving  mechanism  are  bushed  with  bronze  and  oiled 
from  pockets  on  the  outside  of  the  case. 

The  friction  clutch  in  the  machine  driving  pulley  is  of  novel  design. 
The  driving  pulley  A  carries  a  split  friction  ring  T  and  T^,  which  is  ex- 
panded by  the  two  hardened  rolls  S  and  *S^  on  the  end  of  the  sliding  gear 
B.  These  rolls  operate  against  the  hardened  shoes  U  and  U^,  the  inner 
surfaces  of  which  are  arcs  of  circles.  The  sliding  gear  B  is  operated  by 
a  conveniently  located  hand  lever. 

To  operate  the  friction,  the  rolls  are  forced  in  between  the  shoes  a 
little  beyond  the  centers  of  the  arcs,  thus  expanding  the  ring  and  clamp- 
ing it  to  the  pulley.  As  the  rolls  are  beyond  the  centers  of  the  arcs, 
they  remain  locked  in  position.  To  compensate  for  wear,  the  friction 
ring  is  adjusted  by  the  screw  IF,  and  clamped  by  the  set  screw  X. 


CHAPTER   VI 

The  Cleveland  Automatic  Turret  Machine   axd  its  Cam 

Adjust.mexts 

One  of  the  types  of  turret  machines  made  by  the  Cleveland  Auto- 
matic Machine  Company,  Cleveland,  Ohio,  is  illustrated  in  Figs.  45,  46,  and 
47.  The  latter  is  in  reality  a  plan  view  of  a  different  size  of  machine  than 
that  shown  in  Figs.  45  and  46,  but  the  construction  is  essentially  the  same. 


lici.  4.').  — C'lc'VLland  Automatic  Turret  Machine 


SPINDLE    DRIVE 

On  the  Cleveland  machines,  except  in  the  cases  of  those  built  for  light 
forming  and  brass  work,  which  are  direct  driven,  the  spindle  is  driven 

67 


68 


THE   CLEVELAND   AUTOMATIC   TURRET   MACHINE 


by  gears  arranged  on  the  shaft  parallel  to  and  behind  it,  so  that  a  single 
belt  running  continuously  in  one  direction  will,  when  shifted  from  one 


Fig.  46.  —  Cleveland  Automatic  Turret  Machine  (Rear  View) 


Fig.  47.  — Cleveland  Automatic  Turret  Machine  (Plan  \'ie\v) 

pulley  to  another,   drive  the  spindle  alternately  in  opposite  directions, 
as  is  recjuired  in  threading  a  screw  and  backing  off  the  die.     These  gears 


ARRANGEMENT   OF   CAMS  69 

are  usually  so  proportioned  that  the  speed  of  the  spindle  is  greater  when 
running  in  one  direction  than  the  other,  so  that  in  threading  the  die  may 
be  run  off  the  screw  at  a  much  higher  speed  than  is  used  in  cutting 
the  thread.  Other  operations,  including  cutting  off,  may  also  be  run  at 
the  higher  rate  of  speed.  The  movement  for  reversing  the  spindle  when 
threading  is  practically  an  instantaneous  one  and  the  full  width  of  the 
belt  is  used  until  the  operation  of  threading  is  completed.  The  spindle 
carries  the  usual  type  of  spring  chuck  and  feed  tube  for  the  bar  stock. 

TURRET    AND    CROSS    SLIDE 

The  turret  for  carrying  the  tools  is  mounted  on  a  horizontal  shaft 
located  parallel  to  the  spindle.  The  tools  are  held  in  a  concentric  posi- 
tion in  the  front  end  of  the  turret  and  tiie  latter  is  indexed  and  locked 
at  its  periphery  on  a  radius  larger  than  that  of  the  circle  in  which  the 
tools  are  disposed,  thus  serving  to  maintain  proper  alinement  of  the 
tools  with  the  work  spindle.  The  means  of  supporting  the  turret  during 
its  forward  and  backward  movements  in  the  head,  and  the  location  of 
the  longitudinal  indexing  notches  in  its  periphery,  are  shown  clearly,  as 
is  also  the  arrangement  of  the  cross  slide  which  ordinarily  carries  two  tool 
posts,  one  or  both  of  which  may  be  usetl  as  operations  require. 

GENERAL    SYSTEM    OF    OPERATION* 

The  mechanism  for  operating  the  turret  and  the  cross  slide,  as  well 
as  the  stock  feed  and  chuck,  is  driven  through  speed-changing  friction 
disks,  b}'  a  quarter-turn  belt  from  the  countershaft  which  drives  the 
work  spindle.  This  feed-driving  mechanism,  by  means  of  planetary  gears 
and  suitable  clutch  connections,  provides  an  automatically  controlled 
rapid  traverse  for  the  turret  and  cross  slide  during  the  non-cutting  move- 
ments and  a  slow,  readily  regulated  rate  of  travel  during  the  actual  cutting 
operations.  The  method  of  controlling  this  feed  di-ive  will  be  referred 
to  later.  It  will  be  understood,  of  course,  that  turret  and  cross  slide,  feed 
mechanism,  etc.,  may  be  conveniently  operated  by  hand  by  means  of 
crank  handle  and  lever,  when  setting  up  for  a  given  piece  of  work. 

An  inspection  of  the  half-tone  engravings  and  the  line  drawing.  Fig. 
48,  will  reveal  the  location  and  character  of  the  various  cams,  the  means 
of  controlling  the  spindle-driving  belts,  and  other  features  of  impor- 
tance. 

ARRANGEMENT    OF    CAMS 

The  cams  may  be  classed  under  the  following  names:  Turret  cams, 
feed-regulating  cams,  cross-slide  cams,  chuck  opening  and  closing  cams, 
stock-feed  cams.  These  cams  are  all  clearly  shown  in  position,  in  the 
half-tone  engravings,  and  are  represented  also  in  the  drawing.  Fig.  48, 
which  is  a  plan  view  of  the  operating  mechanism. 


70 


THE  CLEVELAND   AUTOMATIC  TURRET  MACHINE 


The  turret  cams  located  just  to  the  rear  of  the  turret,  as  seen  in  Figs. 
45  and  47,  are  shown  at  C  and  D  in  the  diagram.  Fig.  48.  These  cams 
are  fixed  and  are  never  changed.  The  forward  and  back  movements 
of  the  turret  E,  controlled  by  these  cams,  are  constant  for  all  kinds  of 
work;  the  idle  travel  of  the  turret,  before  the  tools  reach  the  work,  is 
made  at  high  speed,  the  cutting  feed  being  tripped  in  just  as  the  tool 


Fig.  48.  — Camming  Diagram,  Cleveland  Automatic  Turret  Machine 

reaches  the  point  at  which  it  is  to  start  cutting.  The  feed  of  the  turret 
to  every  revolution  of  the  spindle  is  variable  to  suit  the  conditions  of 
each  individual  tool  held  in  the  turret.  That  is,  if  there  are  five  cutting 
tools  in  the  turret  and  each  tool  requires  a  different  feed  from  any  of  the 
others,  each  individual  rate  of  feed  is  obtainable  by  means  of  the  adjust- 
able feed-regulating  cams. 


FEED-REGULATING    CAMS 

These  cams,  as  seen  in  the  general  views,  and  at  F,  Fig.  48,  are  strips 
of  flat  steel  I  x  I  inch,  and  each  cam  is  held  in  place  by  two  screws.  The 
cams  may  be  moved  across  the  face  of  the  drum  G,  this  movement  being 
provided  for  by  slots  milled  in  the  drum,  where  the  screws  clamp  the  cams; 
also,  they  may  be  set  at  slight  angles,  taking  peculiar  staggered  positions, 
as  may  be  seen  in  the  drawing.  There  are  two  of  the  cams  for  each  hole 
in  the  turret,  and  the  amount  of  feed  per  revolution  of  spindle  is  con- 
trolled by  these  cams  to  suit  the  individual  requirements  of  each  tool. 

In  setting  these  cams  the  operator  watches  the  cutting  tools  and 
adjusts  the  cams  until  the  tools  are  removing  the  desired  amount  of 


STOCK-FEED  CAM  71 

stock  per  revolution  of  spindle.  A  slight  change  of  angle  on  any  of  the 
cams  produces  a  noticeable  difference  in  the  turret  feed.  The  cams  act 
through  the  medium  of  the  levers  H ,  which  raise  and  lower  the  fiiction 
roll  /  between  the  friction  disks  and  so  give  the  variable  feed.  The  disks 
are  clearly  shown  in  Figs.  46  and  47,  as  well  as  in  the  drawing  just  referred 
to.  The  cams  F  that  are  set  at  an  angle,  or  staggering,  as  they  appear 
in  the  drawing,  are  in  most  cases  intended  for  carrying  the  roll  from  one 
cam  to  another;  that  is,  from  the  cam  set  back  to  the  one  forward,  or  vice 
versa.  There  are,  however,  occasional  cases  when  a  cam  may  be  used 
at  an  angle,  say  in  drilling  certain  holes.  Thus  the  drill  can  start  in  with 
the  feed  decreasing,  or  increasing,  as  it  advances.  When  using  a  drill 
that  is  not  an  oil  feed,  the  lubricant  does  not  reach  the  cutting  edge  as  the 
drill  advances;  for  this  reason  it  may  be  desirable  not  to  feed  the  drill 
so  rapidly,  and  in  such  instances  it  is  advisable  to  use  the  feed-regulating 
cam  set  at  an  angle. 

CROSS-SLIDE    CAMS 

The  drum  J ,  carrying  the  cross-slide  cams,  has  (as  will  be  noticed  in 
Figs.  46  and  47)  a  number  of  rows  of  tapped  holes  around  the  periphery. 
The  cams  A  and  B  are  standard  for  all  work  and  are  adjustable  around 
the  drum.  The  rate  of  feed  of  the  cross  slide  is  variable,  this  also  being 
controlled  through  the  regulation  of  the  cam-shaft  speed  by  the  feed- 
regulating  cams  F,  in  combination  with  the  turret  feed.  If  a  forming 
tool  is  working  in  conjunction  with  a  drill,  the  feed  is  set  for  the  heaviest 
cut  each  tool  will  stand.  If  a  cut-off  tool  is  working  either  in  conjunction 
with  another  tool  or  individually,  tlie  cams  that  take  care  of  this  tool  are 
adjusted  without  interfering  with  other  tools  in  the  different  operations. 

CHUCK    OPENING    AND    CLOSING    CAMS 

These  cams  are  shown  at  K,  and  are  also  visible  in  the  half-tone  illus- 
trations. As  there  shown  they  are  cast  solid  on  the  face  of  a  segment  for 
bar  work,  while  for  magazine  and  double-camming  work  a  drum  is  used. 
For  bar  work  adjustment  is  unnecessary,  as  the  cams  are  cast  in  the  cor- 
rect position  to  allow  ample  time  for  chucking  the  longest  piece  within 
the  capacity  of  the  macliine. 

STOCK-FEED    CAM 

The  stock-feed  cam  L,  which  answers  for  all  work  except  where  double 
feed  is  required,  is  cast  to  the  required  shape  and  clamped  to  the  cam 
shaft.  The  general  f(»i'iii  is  well  illustrated  in  the  rear  view.  Fig.  46, 
where  the  cam  is  shown  just  to  the  left  of  the  cross-slide  di-um.  Its 
adjustments  are  either  around  the  cam  shaft  or  lengthwise  upon  it. 

In  case  double  feed  is  desired,  that  is,  if  it  is  required  to  feed  the  stock 
twice  to  one  revolution  of  the  cam  shaft,  a  drum  is  put  on  the  shaft  in 


il 


THE   CLEVELAND   AUTOMATIC   TURRET   MACHLXE 


place  of  this  segment,  and  two  cams,  which  are  cast  to  the  same  outline 
as  the  segment,  are  fastened  to  the  drum. 

THE    SETTING-UP    FORM 

Fig.  49  illustrates  a  printed  form  that  accompanies  machines  that  are 
tooled  and  covers  all  adjustment  necessar}^  in  doing  any  class  of  work. 

POSITION  OF  TOOLS  AND  CAMS  ON  THE  CLEVELAND  AUTOMATIC 
Sample  No. Order  No Mach.No 


Position  of  Tools  in  Turrent 

Position  of  Regulating  Cams  at  R 

1 

1 

^ 

Regulating  Drum 

2 

P 

2 

3 

o 
o 
o 

o 

4 

P 

3 

5 

8 

M 

1 

7 

U 

8 

5 

0 

2J 

P ' 

10 

6 

11 

P 

12 

Position  of  Cross  Slide  Cnms' 


Cross  Slide  Drum 


Tools  on  From  of  Cross  Slide 


Tools  on  Back,  of  Cross  Slide 


Pieces  per  Honr 

Extra  Tools  and  Aiiachmenib 

fievolutlons  of  Countevshaft  psr  Afiiintp 

Size  of  Flange  Pulley 

Size  of  Spindle  Palley 

Pins  in  KegtUaring  Drum  ontside 

Pins  in  Rpgnlnrmg  fnif'  insirlp 

Kemarks. 



Fig.  49.  —  Setting-up  Chart  for  Cleveland  Automatic. 
(Actual  Size  6  X  12  inches) 

The  feed-regulating  drum,  shown  at  G,  Fig.  48,  and  the  cross-slide  drum 
J  are  both  represented  on  this  sheet,  which  is  designed  to  simplify  the 
setting  up  of  the  machine  when  changing  from  one  job  to  another. 


ATTACHMENTS   AND   TOOLS 


73 


SPEEDS,    FEEDS,    ETC. 

The  countershaft  diagram  is  included  in  the  drawing,  Fig.  48,  M  being  a 
three-step  cone  belted  from  the  main  line;  .V  the  drum  from  which  the  spin- 
dle-operating pulleys  0  are  driven;  P  a  pulley  for  driving  the  feed  mech- 
anism througli  the  medium  of  a  quartei'-turn  belt  i)assing  over  i)ulley  Q. 

In  setting  up  a  job  on  the  machine,  the  speed  at  which  the  spindle 
must  revolve  in  order  to  get  the  peri})heral  speed  of  work  best  adapted 
to  the  tools  is  the  first  consideration  and  is  obtained  by  placing  the  belt 
from  the  line  shaft  on  the  most  suitable  of  the  three  steps  of  countershaft 
pulley  M,  giving  a  fast,  medium,  or  slow  countershaft  speed.  As  the  tool 
feed  is  variable  between  widely  separated  extremes  of  feed,  the  changing 
of  the  speed  of  the  countershaft  does  not  affect  the  feed  of  the  tools,  as 
the  feed-regulating  cams  F  are  adjusted  to  accommodate  the  faster  or 
slower  speeds  of  tiie  countershaft  and  produce  the  desired  rate  of  feed 
of  the  cutting  tools  per  revolution  of  work, 

ATTACHMENTS    AND   TOOLS 

A  number  of  useful  attachments  are  made  for  this  machine  and  two 
of  these  are  shown  in  Figs.  50  and  51.  The  independent  cut-off  attach- 
ment is  designed  to  be  used  in  cases  where  the  forming  to  be  done  is  too 
long  for  one  forming  tool  and  without  this  attaciiment  would  have  to 


Fig.  50.  —  Iiidopendcnt  Cut-olY  Attachmcr.t 

be  partly  formed  on  the  automatic  machine  and  finished  by  a  second  oper- 
ation in  another  machine.  Hy  using  the  independent  cut-off  device  two 
forming  tools  can  be  used;  one  on  the  fi'ont  of  the  cross  slide  and  one  on 
the  rear;  the  piece  being  cut  off  by  the  attachment  whicli  is  in  no  way 
connected  with  tiie  cross  .slide,  but  rests  on  the  hood  of  the  live  spindle 


74 


THE   CLEVELAND   AUTOMATIC   TURRET   MACHINE 


and  the  cam  shaft,  and  is  operated  by  a  cam  on  the  hitter.     In  this  way 
the  piece  is  completely  finished  on  the  automatic  machine. 

THIRD    SPIXDLE-SPEED    ATTACHMENT 

Another  important  device  is  the  third  spindle-speed  attachment  by 
which  a  slow  spindle  speed  forward  is  obtained  in  addition  to  the  regu- 
lar forward  and  reverse  speeds.  This  attachment  is  of  service  especially 
when  taking  heavy  cuts  or  threading  work  of  large  diameter  and  coarse 
pitch.  With  the  belt  on  pulley  A,  Fig.  51,  the  normal  speed  is  obtained; 
with  the  belt  on  pulley  B  and  clutch  C  in  operative  position,  the  slow 


Fig.  51.  —  Third  Spindle-Speed  Attachment 


spindle  speed  is  derived  through  the  medium  of  the  planetary  gears. 
When  the  belt  is  on  pulley  D  the  rapid  reverse  speed  is  secured  for  back- 
ing off  the  die  or  for  cutting  off  the  stock.  Clutch  C  is  controlled  by 
cams  on  clrum  E  and  is  engaged  with  pinion  F  to  hold  the  pinion  fast 
when  the  spindle  is  to  be  driven  at  slow  speed  by  operating  the  belt  on 
pulley  B.  When  the  clutch  is  disengaged,  releasing  pinion  F,  B  becomes 
a  loose  pulley. 

The  magazine  attachment  is  not  illustrated  here  as  it  is  shown  in 
position  on  a  Cleveland  machine  in  Chapter  XIV. 

TURRET    TOOLS 

A  few  typical  turret  tools  are  illustrated  in  Figs.  52  to  57.     The  first 
of  these  is  a  roller  rest  box  tool  with  independently  adjustable  rolls  to 


TURRET  TOOLS 


75 


accommodate  different  sizes  of  stock,  and  with  three  turning  tools  adapted 
to  be  adjusted  in  the  manner  indicated.  The  block  nearest  the  inner 
end  of  the  i)ox  tool  carries  an  auxiliary  steady  rest  with  a  roll  at  its  end 
which  may  be  applied  when  the  work  is  reduced  to  such  a  small  diam- 
eter that  it  is  liable  to  sprinsi-  away  fioni  the  cutting  tool  which  is  shown 


Fig. 


Roller  Rest  Bo.\  Tool 


opposite  the  rest  in  a  vertical  position.  Fig.  53  shows  a  combination 
drilling  and  chamfering  tool.  Fig.  54  is  an  adjustable  boring  tool  which 
may  be  used  w^here  it  is  necessary  to  secure  perfect  concentricit}'  with 
the  exterior  of  the  work.  Fig.  55  is  a  die  and  tap  holder  in  which  the 
socket  for  the  die  ov  the  tap  is  connected  with  the  hnldoi'  pi-oper  by  a 


C"()nil)iiiation  Drilliuff  ami  C'hainfcriii":  Tool 


pair  of  rolls  operating  in  oppositely  located  slots.  This  gives  the  thread- 
ing tool  considerable  freedom  longitudinally  and  assures  accurate  results 
even  though  the  turret  itself  is  not  fed  forward  at  the  exact  speed  with 
which  the  die  is  drawn  onto  the  work.  Fig.  56  is  a  roller  steady  rest 
used  where  it  is  advisable  to  support  a  piece  of  work  undergoing  forming 


76 


THE   CLEVELAND   AUTOMATIC   TURRET   MACHINE 


operations.     The  method  of  adjustment  is  sufficiently  clear  to  require 
no  explanation. 

COMBINATION    UNDERCUT    FORMING    AND    CUT-OFF    TOOL 

This  style  of  tool,  shown  in  Fig.  57,  is  used  very  extensively  on  the 
Cleveland  machines.  It  will  be  noticed  that  it  has  an  adjusting  wedge 
so  that  the  work  diameter  can  be  varied  more  or  less.     In  using  the  form- 


FiG.  54.  —  Adjustable  Boring  Tool. 

ing  tool  in  combination  with  a  cut-off  tool,  the  undercutting  tool  is  set 
in  advance  of  the  cut-off;  in  other  words,  it  passes  under  the  work,  com- 
pleting the  outside  of  the  piece  and  keeps  in  advance  while  the  cut-off 


Fig.  55.  —  Tap  and  Die  Hokler 

tool  is  severing  the  piece  from  the  bar.  In  combination  with  the  forming 
tool  it  rounds  the  corner  or  produces  any  shape  desired  before  the  cut- 
off tool  on  the  opposite  side  of  the  slide  has  advanced  to  sever  the  piece. 

MACHINE    CAPACITIES 

The  regular  turret  machines  of  the  type  illustrated  in  this  chapter 
are  built  in  a  wide  variety  of  sizes;  the  smallest  having  a  chuck  capacity 
of  ^-inch  and  turning  lengths  up  to  1|  inches,  while  the  largest,  which  is 
intended  for  handling  tubing  of  large  diameter  and  for  forming  bevel 
gears  and  other  parts  from  the  bar,  admits  6-inch  material  through  the 
>chuck  and  is   capable  of  turning  lengths  up   to  6f  inches.     A  line  of 


MACHINE  CAPACITIES 


77 


"plain  automatics,"  operated  on  the  same  principle,  as  the  machine 
described,  are  built  with  a  single  tool  head  in  place  of  the  regular  turi-et. 
These  are  intended  es])ecially  for  manufactui'ing  studs,  I'ollei's,  sjiort  screws, 


Fit:.  56.  —  Roller  Steady  Rest 

taper  pins,  etc.,  where  the  forming  may  be  done  entirely  with  the  cross- 
slide  tools.  .Several  sizes  of  automatic  chucking  machines  are  also  built 
by  this  company,  the.se  being  adapted  for  finishing  castings  and  forgings 


Ik..   .')7.    -  Coinhiiiatioii  I'lidercvit  Forming  aii<l 
Cut-off  Tool 

which  are  handled  in  jaw  chucks  or  on  face  plate  fixtures.  The.se 
machines,  in  general  design  and  operation,  are  similar  to  the  regular 
turret  machine  illustrated. 


CHAPTER   VII 

The  Gridley  Sixgle-Spixdle  Automatic  Turret  Lathe 

This  machiiiG,  built  by  the  Windsor  Machine  Company,  Windsor, 
Vermont,  is  designed  for  handling  bar  stock  up  to  2  inches  diameter 
and  for  turning  lengths  of  8  inches,  the  feed  of  the  turret  tools  being 


Fig.  58.  —  Gridley  Automatic  Turret  Lathe 

slightly  in  excess  of  the  latter  figure.  It  is  equipped  with  a  spindle 
geared  from  a  back  shaft  in  the  ratio  of  3  to  1  and  driven  by  2f-inch  belts 
operating  on  11-inch  pulleys.  The  pulleys  are  driven  at  two  different 
speeds  by  open  belts,  except  when  it  is  necessary  to  reverse  the  spindle, 
then  one  is  driven  by  cross  belt  in  opposite  direction. 

78 


Tin-:  TrRRET 


THE    SPINDLE    AND    CHUCK 


The  spindle  is  fitted  with  the  u.sual  type  of  spring  collet  and  feed 
chuck,  and  the  chuck  i.s  operated  by  cams  at  the  inner  edge  (jf  the  drum 
siiowii  to  the  left  in  the  general  \'ie\v.  Fig.  58,  while  the  feeding  of  the  stock 
is  accomplished  b}'  a  weighted  sliding  block  engaging  the  rear  end  of  the 
feed  tube,  the  weight  drawing  the  stock  forwai'd  as  the  chuck  is  opened 
(whicli  movement  takes  place  just  as  the  high  jxjint  of  the  large  cam  at 
the  outer  edge  of  the  drum  passes  the   contacting  roll   under  the  feed 


Fig.  5'J.  —  Gridley  ."Spindle  Construction 

block),  but  the  incline  on  the  heel  of  the  cam  preventing  abrupt  thi-owing 
of  the  bar  against  the  stock  stop  carried  by  the  turret.  The  construc- 
tion of  the  spindle  and  its  driving  mechanism  is  shown  in  the  sectional 
drawing.  Fig.  59. 

THE    TURRET 

The  turret  is  four-sided,  with  as  many  longitudinal  gil)l)ed  slides  for 
the  tools,  and,  as  shown  in  Fig.  60.  is  cast  integi-ally  with  a  long  hub  of 
large  diameter  extending  through  the  bed  of  the  machine.  This  hub 
or  spindle  is  hollow  and  through  it  pa.s.ses  a  shaft  which  at  the  rear  entl 
carries  a  crosshead  and  roll  .i,  which  in  connection  with  the  cams  B  and 
C  on  the  face  of  the  feed  drum  reciprocate  the  shaft  and  operate  the  tool 
slides  on  the  turret.  Only  that  tool  which  is  in  working  position  is 
affected  by  the  movement  of  the  shaft,  however,  as  connection  between 
the  shaft  and  any  tool  .slide  is  made  only  when  that  particular  slide  swings 
up  into  line  with  the  woi-k  spindle.  This  connection  is  effected  by  a  pin 
D  under  the  slide,  and  which  at  the  proper  moment  enters  a  notch  in  a 
dog  carried  by  the  shaft  E.     As  the  tuiTCt  makes  its  next  partial   rota- 


80 


THE    GRIDLEY   SINGLE-SPINDLE   AUTOMATIC   TURRET   LATHE 


tion,  the  connecting  pin  clears  the  engaging  dog  and  the  pin  under  the 
succeeding  slide  enters  that  notched  member.  Feed  cams  of  three  angles  are 
regular!}^  included,  these  being  suitable  for  fine,  medium,  and  coarse  feeds. 
The  cams  are  readily  located  about  the  drum  in   any  required  position. 


"■' 

-^■^N 

(i7r 

->V' 

'vV*^ 

->)  n 

Z.^/ 

Fig.  60.  —  Gridley  Turret  Construction 


CAM-SHAFT    DRIVE 

The  cam  shaft  is  driven  by  worm  wheel  and  worm  shaft  actuated  by 
the  well-known  differential  gear  or  "sun  and  planet"  mechanism,  the 
quarter-turn  belt  being  shifted  at  the  proper  moment  from  fast  to  slow 
driving  position,- or  vice  versa,  by  a  forked  guide  operated  through  the 
medium  of  adjustable  dogs  carried  by  a  disk  on  the  cam  or  main  shaft. 
This  feed,  as  seen  in  Fig.  61,  may  be  thrown  out  of  action  at  any  time  by 
turning  a  small  handle  at  the  front  of  the  bed,  this  handle  being  attached 
to  a  shaft  carrying  at  its  rear  end  the  pawl  which  locks  the  ratchet  wheel 
in  this  form  of  drive.  Of  the  two  pulleys,  F  is  the  one  driving  through 
planetary  gears,  the  pulley  making  70  revolutions  to  one  turn  of  the 
worm  G.  When  the  belt  is  shipped  onto  pulley  //,  which  is  pinned  to  the 
worm  shaft,  the  cam  shaft  is  rotated  rapidly  for  moving  the  tools  to  or 
from  their  cuts  at  high  speed. 

TURRET    REVOLVING    AND    LOCKING    MECHANISM 

The  turret  rotating  mechanism  is  driven,  as  in  Fig.  62,  by  an  inde- 
pendent worm  and  worm-wheel,  also  rotated  by  a  quai'ter-turn  belt  at 
the  rear  of  the  bed. 

The  locking  disk  A  is  keyed  to  the  stem  B  of  the  turret  and  carries 


TURRET   REVOLVING   AND   LOCKING   MECHANISM 


81 


Fig.  61.  —  Feed  Drive  for  Cam-Drum  Shaft 


Policy  DriTcn  coDtinroiulj 
at  a  CooBtaot  Sp««a, 


Left  Hand 
End  Elevation 


igjit  Hand 
End  Elevalioa 


Fig.  62.  —  Turret  Hevohing  and  Locking  Mechani.sm 


82         THE   GRIDLEY   SINGLE-SPINDLE   AUTOMATIC   TURRET   LATHE 

4  tool  steel  shoes  C  into  which  the  locking  pin  D  enters.  The  locking 
pin  is  withdrawn  by  the  lever  E  with  its  shaft  E^  and  arm  E-,  the  upper 
end  of  which  enters  a  hole  in  the  locking  pin.  The  lever  E  is  operated 
bv  the  roll  F,  which  is  fastened  in  the  edge  of  the  cam  drum.  This  is 
the  cam  drum  between  the  columns  of  the  frame.  When  this  lever  E 
has  been  moved  forward  far  enough  to  draw  the  locking  pin  clear  from 
the  seat  C,  the  arm  E^,  attached  to  the  lever  E,  raises  the  latch  G,  and 
the  spring  H  slides  the  shaft  /  with  its  clutch  member  /^  into  engage- 
ment with  the  other  clutch  member  /,  which  is  driven  constantly  by  the 
shaft  J^  and  its  pulley  J-;  this  causes  the  shaft  I  to  revolve,  and  that  in 
turn  revolves  the  worm  K,  thus  causing  the  turret  through  the  worm  K 
and  worm  gear  L  to  revolve. 

It  will  be  noticed  that  the  end  of  the  locking  pin  rides  on  the  periphery 
of  the  locking  disk  A  after  the  roll  F  has  passed  the  projection  on  E. 
When  the  turret  has  revolved  so  that  the  locking  pin  drops  into  the  notch  in 
seat  C,  the  shaft  I  with  its  clutch  is  moved  endwise  out  of  engagement  with 
the  constantly  revolving  member  J,  by  the  pin  M  in  the  lower  end  of  the 
lever  E-.  In  order  to  take  care  of  the  momentum  of  the  revolving  parts 
and  clutch  P,  which  is  geared  with  the  turret  through  the  worm  K  and 
worm  gear  L,  a  spring  .V  is  interposed,  one  end  of  which  bears  against  the 
bracket  which  carries  the  revolving  parts,  and  the  other  end  against  the 
worm  K,  so  that  when  the  turret  stops  revolving,  the  spring  A''  allows 
the  worm  K  to  act  as  a  screw,  the  worm  gear  L  acting  as  a  nut,  so  that 
it  is  not  necessary  to  stop  the  movement  of  the  revolving  parts  instantly. 

The  worm  K  is  splined  to  a  bushing  0,  but  is  free  to  move  endwise 
on  the  bushing,  the  latter  being  splined  to  the  shaft  /.  The  object  of 
the  latch  G  and  the  spring  H  is  to  prevent  the  engagement  of  the  clutches 
F  and  /  until -the  locking  pin  D  has  been  entirely  withdrawn  from  the 
inserted  shoe  C,  then  the  further  movement  of  the  lever  E  with  its  arm 
E^  raises  the  latch  G  out  of  engagement  with  the  collar  /-  on  the  shaft  /. 
The  movement  of  the  lower  end  of  the  lever  E'^  compresses  the  spring  //, 
&o  that  when  the  latch  G  is  clear  of  the  collar  P,  shaft  /  is  given  a  quick 
endwise  motion  to  bring  the  two  clutch  parts  together.  There  is  a  leather 
ring  on  each  of  the  clutch  parts  so  that  when  they  are  brought  together 
by  the  spring  H  the  turret  is  operated  by  the  frictional  contact  between 
the  leather  rings.  In  fact  the  frictional  engagement  oftentimes  accom- 
plishes the  revolving  of  the  turret  without  the  necessity  of  the  steel 
clutches. 

THE    CROSS    SLIDE 

The  cross  slide  is  operated  by  a  cam  under  the  turret.  It  is  fitted  to 
a  heavy  guide  and  a  broad,  taper,  adjustable  shoe  is  fitted  to  the  top  of 
this  guide  to  take  up  any  play.  The  slide  may  be  utilized  for  either  form- 
ing or  cutting-off   operations.     When  it  is  used  for  forming,  the  cut-off 


THE   TURRET   TOOLS 


83 


tool  is  carried  in  the  pivoted  arm  at  the  back,  this  arm  also  being  oper- 
ated bv  a  cam  on  the  disk  beneath. 


THE    TURRET   TOOLS 


The  slides  carried  by  the  turret  give  plenty  of  room  for  tools  of  any 
class  or  size  likely  to  be  required;  each  slide  is  provided  with  a  longi- 
tudinally placed  screw  for  ailjusting  the  tools  accurately  to  and  from 
the  spindle.     Where  de-ire<l,  the  stock  stop  may  bo  clamped  in  one  of 


Fig.  (i'-i.  —  Tunet  with  Drill  ami  Guide  in  Position 

the  corners  of  the  turret,  thus  leaving  all  four  faces  clear  for  cutting  tools, 
and  when  so  arranged,  an  extra  notch  is  provided  in  the  index  disk  to 
stop  the  turret  in  an  intermediate  position.  By  dropping  a  block  into  one 
or  more  notches  in  the  index  disk  the  turret  may  be  allowed  to  skip  one 
or  more  stations,  thus  turning  cjuickly  through  two  or  more  points  in  its 
rotation  before  it  is  acain  lock?d. 


riG.  64.  — Turner  with  Roller  Back  Rests 

Two  tools  may  be  placed  in  tandem  order  on  any  slide,  and  when  drill- 
ing long  holes  the  drill  may  be  secured  —  as  in  Fig.  68  —  in  a  holder  at 
the  rear  while  an  auxiliary  block  at  the  front  carries  a  supporting  bush. 
The  turning  tools  are  equipped  with  roller  back  re.sts  as  in  Fig.  64,  and  to 


84 


THE   GRIDLEY   SINGLE-SPINDLE   AUTOMATIC    TURRET   LATHE 


each  tool,  as  well  as  to  drills,  there  is  an  oil  supply  which  can  flow  to  the 
tool  only  when  the  latter  is  in  operating  position.  The  oil  piping  will 
be  seen  in  the  various  illustrations. 


Fig.  65.  —  Turning  and  Forming 

Fig.  65  shows  a  turner  and  cross-slide  tool  in  operation,  and  Fig.  66 
illustrates  a  12-inch  finishing  slide. 


TWELVE-INCH    FINISHING    SLIDE 

The  object  of  this  tool,  which  is  primarily  a  finishing  device,  is  to  take 
a  longer  cut  than  the  cams  or  the  turret  itself  will  admit.  The  regular 
feed  cams  will  give  only  an  8J-inch  movement,  but  with  this  tool  a  straight 
cut  12  inches  in  length  can  be  taken,  and  allow  f-inch  clearance.  This 
is  accomplished  by  having  a  rack  under  the  slide  operated  by  the  regular 


Fig.  66.  —  Twelvc-incli  Finishing  Slide 

draw  bar  in  the  usual  manner.  This  rack  runs  in  a  pinion,  onto  which 
is  fastened  a  large  gear  which  in  turn  runs  in  a  rack  attached  to  the  tool 
slide,   and  the  rack  operated  by  the  draw  bar  thus  gives  an  increased 


DIE   HOLDER 


85 


movement  to  the  rack  attached  to  the  tool  slide.  To  use  the  tool  the 
regular  slide  is  taken  out  of  the  turret  and  the  12-inch  slide  put  in  its 
place. 


TAPER    TURNER 


A  taper  turner  is  shown  in  Fig.  67.     It  carries  two  tools,  one  of  these 
carried  in  post  A  preceding  the  back  rest  jaws  B,  giving  the  work  a  true 


A- 

n 

d 

I 

^iqj 

1 

j 

1 

Fig.  67.  ■ —  Taper  Tumor 

cylindrical  surface,  while  the  tool  C  following  tiie  back  rest  is  carried  by 
a  cross  slide  D  whose  movements  are  controlled  by  the  taper  bar  shown 
at  the  rear, 

DIE    HC^lDER 

A  method  of  mounting  an  opening  die  on  the  turi-et  is  shown  in  Fig. 
68,  where  the  die  is  mounted  in  a  sliding  sleeve  which  is  held  back  in 
normal  position  by  a  light  spring,  tiie  head  in  this  position  resting  against 
a  cushioning  compression  spring  which  pievents  the  die  striking  the  work 
al)ruptly  as  it  feeds  forward.  Tlie  die  once  started  on  the  cut,  the  turret 
slide  stops  and  the  slitling  carrier  then  moves  forwai'd  in  its  holder  until 
an  opening  lever  on  the  die  head  strikes  an  adjustal)le  sto])  bar  shown 
just  below  the  die  proper.  This  opens  the  chasers,  and,  as  the  turret 
slide  returns,  the  bent  lever  at  the  side  of  the  die  comes  into  contact  with 
another  stop  secured  in  the  corner  of  the  turret,  and  by  turning  the  tlie 
head  slightlv  closes  it  for  the  next  cut. 


86        THE   GRIDLEY   SINGLE-SPINDLE   AUTOMATIC   TURRET   LATHE 

The  method  of  belting  from  the  countershaft  will  be  understood  from 
Fig.  69,  no  explanation  being  called  for. 


MOTOR    DRIVING    AND    CONTROLLING    ARRANGEMENT 

An  interesting  form  of  the  Gridley  automatic  turret  lathe,  in  which 
both  the  work  spindle  and  cam-drum  shaft  are  driven  by  variable-speed 


Fig.  68.  —  Turret  with  Opening  Die  in  Place 

motors  the  controllers  of  which  are  operated  automatically  by  cams  on 
one  of  the  drums,  is  shown  in  Figs.  70  and  71.  This  arrangement  gives 
a  very  flexible  control  of  cutting  speeds  and  feeds  throughout  the  cycle 
of  operations  required  to  produce  any  given  piece  of  work. 

This  type  of  motor-driven  machine  is  made  in  two  sizes,  one  taking 
bar  work  up  to  3^  inches,  and  the  other  up  to  4^  inches  diameter.  The 
variable-speed  motor  for  the  spindle  is  mounted  as  represented  in  the 
engravings,  at  the  top  of  the  head-stock  and  behind  the  spindle.  The 
motor  shown  is  a  General  Electric  3-horse-power  machine  geared  10  to  1 
to  the  spindle. 

CAM-SHAFT    DRIVE    AND    MOTOR    CONTROL 

The  variable-speed  motor  operating  the  drum  shaft  and  the  turret- 
revolving  mechanism  is  fixed  to  a  bracket  wdiich  is  attached  to  the  oil 
pan  and  the  rear  column  of  the  machine,  as  shown  in  Fig.  71.  Both 
motors  are  operated  by  controllers  placed  near  the  floor  at  the  front  side 
of  the  machine.  The  metal  tubing  incasing  the  armature  and  field  wires 
from  the  spindle  motor  to  its  controller  is  shown  in  Fig.  70,  while  in  the 
end  view  the  wires  from  the  feed  motor  to  its  controller  are  seen  follow- 
ing the  top  of  the  oil  pan.  The  controllers  themselves  are  operated  auto- 
matically by  a  small  gear  beneath  the  controller  handle  meshing  with  a 
segment  gear  pivoted  on  the  frame  holding  the  controllers,  the  segment 
gear  being  moved  as  desired  by  cams  bolted  to  the  operating  drum.  By 
using  different  cams  any  desired  speed  may  be  obtained  for  the  spindle 


SPEED   AND    FEED    ^•APJATIO^• 


87 


motor,  or  it  may  be  entiroly  stopped  while  the  tools  are  withdrawn  from 
finished  work. 

SPEED    AND    FEED    VAUIATIOX 

In  threading  work,  inside  and  out,  advantage  is  gained  by  slowing 
the  spindle  motor  to  the  proper  threading  speetl,  and  then  reversing  at 
full  speed  for  backing  off  or  out  solid  dies  or  taps.  This  not  only  saves 
considerable  time,  but  by  having  the  proper  cutting  speeds  better  threads 
are  obtained.  The  variable-speed  feed  motor  in  combination  with  the 
four  sets  of  feed  cams  in  the  machine  equipment  gives  the  proper  range 


Fic.  (id. — Countershaft  and  Drive  for  (iriilK'V  Automatic  Turret  Lathe 


of  feeds,  from  that  reciuired  in  drilling  tool  steel  to  the  coarsest  roughing 
cut  a  ^  X  1  inch  high-speed  roughing  tool  fiooded  with  oil  will  stand.  The 
wide  range  in  both  speeds  and  feeds  instantly  obtainable  for  every  opera- 
tion, with  also  a  variable  reverse  speed  of  the  spindle,  enable  the  machine 
to  handle  to  advantage  any  work  within  its  capacity.  The  fast  ami  slow 
motion  for  the  drum  shaft  is  obtained  by  tlriving  the  worm  direct  from 
the  feed-shaft  motor  or  back-geared  through   planetary  gears,  operated 


88        THE   GRIDLEY   SINGLE-SPINDLE   AUTOMATIC   TURRET   LATHE 

by  the  same  cams  as  are  used  on  the  belt-driven  machines  for  this  pur- 
pose. 


Fig.  70.  —  Gridley  Motor  Operated  Turret  Lathe 


Fig.  71.  —  Gridley  Motor  Operated  Turret 
Lathe  (End  View) 

The  tools  used  on  this  machine  are  of  the  same  general  type  as  already 
shown  in  connection  with  the  Gridlev  belt-driven  automatic. 


CHAPTER    VIII 


The  Alfrf:d  Herbert  Automatic  Screw  Machixk 

The  accompanying  half-tone.  Fig.  72,  illustrates  the  automatic  turret 
machine  built  by  Alfred  Herl)ert,  Ltd.,  Coventry,  England.  The  machine 
shown,  which  is  one  of  the  larger  sizes  made  by  this  concern,  will  admit 
a  3^j-inch  bar  through  the  sj^ndle  and  will  turn  up  to  a  length  of  8  inches. 
It  is  illustrated  as  fitted  up  for  producing  shells  for  (juick-firing  guns. 


Fig.  72. 


Alfred  lIcrlnTt  Automatic  Scivw  .Macliiii 


The  ai-rangement  of  the  cam-shaft  drive,  and  cam  drums,  the  cross- 
slide  mechanism,  etc.,  are  clearly  brought  out  in  the  general  view.  The 
spindle  with  its  spring  collet  and  stock-feeding  apparatus  is  driven  by 
a  shaft  at  the  rear  to  which  it  is  connected  by  gear  and  pinion,  the  driving 
shaft  being  operated  l)y  a  pair  of  belts  from  the  overhead  works.  The 
arrangement  is  such  that  both  of  the  belts  can  be  open  and  one  of  them 
faster  than  the  other  where  it  is  desirable  to  change  the  speed  of  the  work 
during  its  progress,  as  for  tapping  or  external  threading,  the  speed  chang- 
ing automatically  the  same  as  though  it  were  reversing. 

89 


90 


THE   ALFRED    HERBERT   AUTOMATIC   SCREW   MACHINE 


The  type  of  tools  used  in  turret  and  cross  slides  is  shown  clearly. 
A  number  of  turret  tools  are  also  illustrated  in  Fig.  73.  One  of  the  tools 
in  the  group  is  the  Coventry  opening  die,  and  this  die  is  also  illustrated 
mounted  in  a  spring  holder  in  the  turret  and  with  the  operating  cam  at 
the  side  of  the  latter.  The  magazine  machines  built  by  this  company 
are  described  in  Chapter  XV. 


1.    Drill  Holder  and  Bushing.  2.    Centerino;  and  Facing  Tool. 

3.    Box  Tool  with  Two  Cutter  Blocks.  4.    Steady  Bush  Holder. 

5.    Coventry  Opening  Die.  6.    Opening  Die  in  Turret. 

Fig.  73.  —  Tools  for  Herbert  Automatic  Screw  Machine 


CHAPTER   IX 

New  Spencer  Douhle-Tihhet  Automatic  Screw  Machine 

The  Spenc'or  screw  inacliino,  with  its  two  tuiTet.s,  as  now  built  by 
the  Mack  Maimfactiiriiiii;  Company,  Jersey  City,  N.  J.,  is  illustrated 
in  Fi<2;.  74.  It  handles  stock  up  to  1^  inches  thr()Uo;h  the  hollow  spindle 
and  finishes  both  ends  of  a  j)iece  without  reniovinq;  it  fi'oni  tlie  machine. 


I'k;.   74.  — Speiicor  lJ()ul)L'-Turn't  Autoinatic  Screw  Mac'iiiu' 

The  (ii'um  at  the  left  carries  the  cam  stiips  which  conti'ol  tlie  stock 
feed  and  the  chuck  of  the  main  spindle.  Next  come  the  two  disks  with 
cams  for  controllin.si'  the  belt  movement  in  eitlier  direction;  then  the  cut- 
off and  formino-tool  cam  disk  under  the  cut-off  slide;  the  friction  disk 
Avhich  revolves  the  turrets  at  the  proper  time;  two  more  belt-shifter  disks; 
the  worm-feed  mechanism  for  revolving  the  drum  or  cam  shaft  and  the 
large  drum  with  the  cams  for  the  first  or  left-hand  turi-et;  the  cams  for  the 
secondary  spindle  movement,  and  for  controlling  the  chuck  in  this  spindle. 

The  two  turrets  are  mounted  on  spindles  at  the  back  of  the  machine, 
the  spindle  for  the  left-hand  tui'ret  telescoping  through  tlie  (luill  on  which 
the  right-hand  turret  is  mounted.  The  latter  does  not  move  endwise, 
but  the  work  is  fed  to  the  tools  of  this  turret. 

The  first  turret  is  fed  to  tlie  work  tliiough  the  (juill,  and  both  turrets 

91 


92       NEW   SPENCER  DOUBLE-TURRET  AUTOMATIC  SCREW  :\L\CHINE 


are  made  to  revolve  together  by  two  studs,  fastened  in  one  turret  and 
sliding  in  the  other,  as  can  be  seen  above  the  secondary  spindle. 

The  stops  are  carried  in  the  outer  edge  of  the  first  turret  and  rest 
against  the  plate  shown,  which  also  guides  the  tools  in  line  to  their  work. 
The  cams  draw  the  stop  off  the  end  of  the  plate  when  it  is  time  to  revolve, 
the  friction  disk  with  the  chain  which  is  constantly  pulling  the  turret 
forward  revolves  it,  the  cam  throws  the  next  stop  over  the  plate  and  the 
next  tool  goes  to  work. 


'^'^~\m 


www 


3i» 


Fig.  75.  — Work  Done  on  Doiil)le-Turret  Machine 

In  operation  the  bar  is  fed  in  through  the  left  or  main  spindle  to  a 
stop  in  the  first  turret,  the  chuck  is  closed  and  the  tools  in  the  left  turret 
commence  operations  on  the  piece.  Taking  any  one  of  the  pieces  shown 
in  Fig.  75,  the  making  of  the  first  end  is,  of  course,  regular  screw-machine 
work.  When  ready  to  cut  off,  however,  the  long  slide  throws  the  second- 
ary spindle  forward,  past  the  open  side  of  the  second  turret,  till  the  chuck 
closes  over  the  end  of  the  work  already  finished.  As  both  the  work 
and  the  secondary  spindle  are  revolving  at  the  same  rate,  there  is  no 
difficulty  in  gripping  it  firmly  and  without  injury. 

Then  the  second  spindle  recedes,  carrying  the  work,  and  the  turrets 
revolve;  while  the  first  turret  is  at  work  on  the  beginning  of  a  new  piece, 
the  second  turret  is  finishing  the  back  end  of  the  piece  in  the  second 
spindle.     In  this  case  the  work  is  fed  to  the  tools. 

When  the  last  operation  is  done,  the  secondary  chuck  opens,  the 
ejector  controlled  by  the  spring  at  the  extreme  right  pushes  the  work 
out  of  the  chuck,  and  it  is  ready  to  go  forward  again,  to  take  a  new 
piece  which  the  first  turret  has  finished  and  is  ready  to  cut  off. 


CHAPTER   X 

The  Cleveland  Double-Spindle  Plain  ArxoMATir  Machine 

The  two-spindle  machine  illustrated  in  Fig.  76  is  designed  primarily 
for  forming  and  shaving  both  ends  of  the  work,  thus  obviating  the  neces- 
sity for  a  second  operation.  It  has,  in  place  of  the  usual  Cleveland  turret, 
a  second  head  carrying  a  spindle  in  line  with  the  main  or  left-hand  spindle 
through  which  the  stock  is  fed  in  the  customary  manner.  After  the  end 
of  the  bar  is  fed  througii  the  left-hand  oi-  main  sj-dndlo  and  is  gi'ipjied  in 


l'i(i.  70.  — t'U'vehuul  D()ul>li'->i)in(ll('  Plain  Auloiiiatii- 

the  chuck,  a  combination  cutting-off  and  forming  tool  advances  and 
completes  the  outer  end  of  the  piece;  it  is  then  fed  through  the  right-hand 
spindle  hood,  the  chuck  mechanism  on  both  spindles  acting  simultane- 
ously. The  piece  then  partly  finished  is  gripped  in  the  right-hand  chuck 
and  the  forming  tool  advances,  finishing  both  ends  as  seen  in  Fig.  77. 
After  the  forming  tool  has  advanced  far  enough  to  separate  the  two  pieces 
it  still  continues  to  feed  forward  for  a  short  distance  until  both  ends  are 
shaved  clean  and  exact  to  size.  As  these  operations  take  place  on  one 
piece  after  another,  the  finished  parts  are  moved  tin-ough  the  right-hand 

93 


94       CLEVELAND    DOUBLE-SPINDLE    PLAIN    AUTOMATIC  MACHINE 


spindle  head,  finally  dropping  into  the  pan  fastened  to  the  end  of  the 
machine.  The  spindle  and  cross-slide  operations  are  controlled  in  prac- 
tically the  same  manner  as  on  the  regular  turret  machine  built  by  the  same 
company  and  illustrated  in  Chapter  \L 


Fig.  77.  —  Work  on  Cleveland  Double-Spindle  Machine 


CHAPTER   XI 

The  Acmio  Multiple-Si'Ixdle  Automatic  Screw  Machine 

The  niultiple-spiiuUe  automatic  screw  machine  built  by  the  National 
Acme  Manufacturing  Company,  Cleveland,  Ohio,  is  illustrated  in  its 
latest  form  with  single-belt  drive  in  Figs.  78  and  70.  When  efjuipped 
for  motor  di'ivc  the  single  driving  pulley  is  replaced  with  a  spur  gear  and 
the  motor  connected  to  tliis  is  carried  on  a  bracket  jjlaced  at  the  l(>ft  of 
the  gear. 


Ik;.   7S.        Acme  .Multiiilo-Spintllo  .Xutonuitic  Screw  Macliii.c 

The  machine  as  shown  consists  ])rimarily  of  a  cylindei-  .1,  Fig.  7S,  hold- 
ing four  stock-carrying  spindles  and  a  series  of  slides  carrying  tools  which 
operate  on  all  four  bars  from  the  side,  top,  and  end  at  one  time. 

As  there  are  two  slides  oj)erating  from  op])osite  sides  of  the  machine, 
two  from  the  top  and   one  (the   main  slide,  which  is  capable  of  cari'ying 


96        THE   ACME   MTLTIPLE-SPINDLE   AUTOMATIC    SCREW   MACHINE 


four  tools,  one  for  each  spindle)  from  the  end,  it  is  possible  to  use  eight 
separate  tools  at  one  time  —  two  on  each  bar,  one  from  the  end  and  one 
from  the  side. 

After  a  bar  has  been  operated  upon  in  the  first  position  by  one  pair 
of  tools,  it  is  carried  on  to  the  next  pair  by  the  cylinder  which  is  indexed 
by  quarter  turns.  In  this  manner,  after  three  sets  of  tools  have  finished 
their  work  upon  the  piece,  it  is  carried  to  the  fourth  position  where  the 
final  tools  (one  of  which  is  a  cutting  off  blade)    operate  upon  it.     This 


Fig.  79.  —  Acme  Multiple-Spindle  Automatic  Screw  Machine  (Rear  View) 

gives  a  finished  piece  at  each  quarter  turn  of  the  cylinder.  As  all  tools 
work  simultaneously,  the  time  required  for  the  longest  single  operation 
is  the  time  necessary  to  finish  the  piece. 

It  is  frequently  possible  to  combine  two  or  more  tools,  such  as  a  box 
tool  and  a  drill,  two  dies,  die  and  tap,  drill  and  countersink,  etc.,  or  to 
use  special  attachments,  described  later.  In  such  cases  more  than  eight 
operations  are  readily  performed. 

The  stock  is  fed  in  the  manner  generally  adopted  on  automatic  screw 
machines,  all  movements  being  cam  controlled  and  positive.  The  length 
of  feed  and  position  of  the  gage  stop  are  easily  changed  to  meet  the  re- 
quirements of  the  work  in  hand.     The  gage  stop  on  this  machine  does 


FEED   rriAXGES 


97 


not  occupy  one  of  the  end  tool  positions,  but  is  so  arranged  that  the  stock 
is  fed  against  it  during  the  quarter  turn  of  the  cylinder  on  the  smaller 
machines,  and  just  before  the  tools  engage  the  stock  in  the  first  position 
on  the  larger  sizes,  the  stop  being  swung  back  to  allow  the  tools  to  come 
into  contact  with  the  stock. 


DRIVING    AND    SPEED    CHANGE    MECHANISM 

The  drive  to  the  four  work  spindles  is  transmitted  by  the  longitudinal 
shaft  and  connecting  gearing  as  illustrated  in  the  general  views  and  in 
Fig.  80,  and  the  speed-changing  mechanism  and  cam-shaft  drive  are 
arranged  as  represented  in  Fig.  SI. 


Acme  Spindle  Dri 


A  change-gear  system  is  used  in  connection  with  these  mechanisms 
in  order  to  transmit  driving  power,  as  well  as  facilitate  rapid  changes  in 
the  spindle  speeds  and  tool  feeds. 

The  stock-spindle  speeds  are  controlled  by  back  gears  .1,  Fig.  81. 
When  running  direct,  gears  on  the  stud  B  are  slipped  out  of  engagement 
with  those  on  the  pulley  hub  and  top  shaft,  or  removed  entirely. 

Direct  drive  is  obtained  by  first  sliding  gears  on  the  stud  out  of  mesh, 
then  binding  together  thimble  C  and  pulley  (or  gear,  if  motor  driven), 
with  the  two  screws  furnished  for  this  purpose.  When  changing  from 
direct  speed,  the  two  thimble  screws  are  removed  before  placing  the  gears 
on  the  stud  in  mesh  witli  tlie  gears  on  the  })ullev  hul)  and  shaft.  To 
change  the  spindle  speed,  tlie  vertical  section  of  overlianging  arm  D  is 
removed  by  removing  screw  E,  after  which  thimble  C  is  removetl,  tlie  pulley 
(or  gear,  if  motor  driven)  slipped  off  of  the  top  shaft  and  the  gears  slipped 
from  the  hub  of  the  pulley  antl  stud,  replacing  with  tlie  gears  to  be  used. 

FEED    CHANGES 

Feed-rate  changes  are  controlled  by  gears  F,  Fig.  81  through  which  the 
cam  shaft  is  operated.  The  idle  movements  of  the  machine  (those  which 
occur  when  the  tools  are  not  operating  on  the  work,  such  as  feeding  in  of 
the  rods,  indexing  of  cylindei",  movement  of  tool  slide  toward  and  from 


98 


THE   ACME   MULTIPLE-8PINDLE   AUTOMATIC    SCREW   MACHINE 


the  work,  etc.)  occur  when  the  machine  is  running  at  the  constant  or 
direct  speed,  or  when  sliding  chitch  G  is  engaged  with  the  teeth  in  cUitch 
collar  H.  Through  the  use  of  roller  clutch  J  the  feed-change  gears  remain 
idle  during  these  movements.  \'arious  classes  of  work  can  be  produced 
at  a  higher  rate  than  is  provided  b}'  the  direct  feed  drive.  This  is  accom- 
plished by  the  use  of  certain  combinations  of  change  gears  and  is  clearly 
set  forth  in  a  gear  table,   supplied  with  the  machine.     The  shifting  of 


Fig.  81.  —  Spindle  and  Cam  Shaft  Change  Gear  and  Driving 
Mechanism 


sliding  clutch  G  is  controlled  automatically  by  arm  K,  Fig.  78,  operated 
by  dogs  or  cams  on  drum  L;  also  by  hand  lever  M.  ^^"ith  the  hand  lever 
to  the  extreme  right,  arm  K  is  removed  from  the  zone  of  the  dogs  or  cams 
on  drum  L,  and  the  feed  mechanism  is  rendered  inoperative,  except  on 
the  slow  or  cutting  speed.  The  lever  cannot  be  moved  in  this  direction 
dui-ing  the  idle  movements,  or  when  the  feed  mechanism  is  being  oper- 
ated on  the  direct  or  fast  speed,   and  when  in  this  position  cannot  be 


CAMS   AND   CAM    SHAFT  99 

moved  to  throw  the  sliding  clutcli  in  engagement  with  the  teeth  of  the 
direct-drive  clutch,  thereby  eliminating  the  possibility  of  trouble  which 
might  be  caused  by  jamming  the  tools  against  the  woi'k  on  the  fast  or 
direct  speed.  This  hand  lever  will  be  found  very  convenient  during  the 
work  of  setting  up  the  machine,  as  by  its  use  the  amount  of  hand  cranking 
can  be  very  materially  retlucetl. 

Clutch  G,  Fig.  81,  should  always  be  in  the  neutral  position  wIkmi  tlie 
hand. crank  is  being  used.  The  shifting  action  of  this  clutch  mav  be 
regulated  by  slight  adjustment  of  angular  cam  \\  and  its  proper  engage- 
ment with  the  stationary  clutches  is  assured  by  tension  on  the  spring  which 
operates  plunger  P,  this  tension  being  increased  if  found  necessary  by 
turning  nuts  R  to  the  right. 

Frictions  S  and  T  are  employed  in  connecting  the  feed-change  gears 
to  the  sprocket  shaft  and  the  small  sprocket  to  the  worm  shaft,  their 
use  being  a  safety  measure  as  they  will  slip  in  case  of  accident  causing 
unusual  strain  on  the  machine,  and  thus  prevent  the  bi-eakage  or  dis- 
tortion of  the  moi'e  vital  parts  of  the  mechanism. 

CAMS    AND    CAM    SHAFT 

The  cam  shaft  carries  the  drums  and  disk  to  which  are  attached  the 
cams  which  control  the  several  movements  of  the  machine,  and  in  addi- 
tion the  indexing  segment  for  the  cylinder  carrying  the  four  woik 
spindles.  The  proper  indexing  of  the  cylinder  depends  upon  the  indexing 
segment,  and  especially  upon  the  last  tooth,  which  is  made  adjustable 
to  compensate  for  such  wear  as  may  occur  at  this  point. 

To  drum  or  disk  B,  Fig.  79,  are  attached  the  cams  or  dogs  which  t)i)er- 
ato  the  lever  controlling  the  change  from  the  idle  to  working  speeds  of 
the  machine,  and  with  the  exception  of  machines  Xos.  51,  515,  and  52 
the  lever  operating  the  thread-starting  mechanism. 

Cam  drum  (',  Fig.  79,  operates  the  main  tool  slide,  and  on  machines 
Nos.  51,  515,  and  52  the  thread-starting  mechanism.  The  grooves  in 
this  drum  are  for  what  are  known  as  the  "  backing-uji"  stiips,  which 
are  used  to  relieve  the  strain  on  tlie  screws  that  liold  the  lead  cam  —  the 
cam  which  feeds  forward  the  main  tool  slide.  The  cross  slots  in  this 
drum  provide  for  adjustment  of  tlie  cam  which  controls  the  rapitl  move- 
ment of  the  tool  slide  toward  the  work  before  the  cuts  are  started. 

Disk  7),  Fig.  7i),  can-ies  the  cams  which  operate  the  cutting-off  and 
forming  tool  slides.  There  are  two  sets  of  screw  holes  in  this  disk  for 
locating  the  cutting-off  cam,  one  set  of  holes  to  be  used  when  there  is  no 
operation  to  be  i)erformed  from  the  fourth  position  of  the  main  tool 
slide,  the  other  when  this  position  is  used.  It  is  necessary  to  use  the  extra 
set  of  holes  when  an  operation  is  being  performed  in  the  fourth  position 
from  the  main  tool  slide  in  ordei'  to  delay  tlie  cutting-off  operation  until 


100      THE   ACME   MULTIPLE-SPIXDLE    AUTOMATIC    SCREW   MACHINE 

the  tool  slide  recedes  sufficiently  to  allow  the  tools  in  the  fourth  position 
to  clear  the  work  before  the  piece  is  entirely  cut  off. 

Disk  E,  Fig.  79,  operates  the  cylinder-locking  levers.  On  the  small 
machines  this  disk  is  outside  the  leg.  Disk  F  operates  the  oscillating 
gage  stop  on  machines  Nos.  53,  54,  55,  and  56.  Machines  Nos.  51  to  52 
are  equipped  with  stationary  gage  stop  and  this  disk  will,  therefore, 
not  be  found  on  these  machines.  Cam  drum  G  carries  the  cams  which 
operate  the  frictions,  chucking  and  un-chucking  levers,  and  feeding  mech- 
anism.    Cam  shaft  end  play  is  taken  up  by  collars  at  L. 

THE    WORK-SPINDLE    CYLINDER    AND    CYLINDER    CASING 

The  cylinder  .1,  Fig.  78,  for  the  work  spindles  is  of  gray  iron,  the 
bearing  surface  of  which  is  ground  to  size.  The  internal  surface  of  the 
cylinder  casing  B  is  also  ground  to  size;  compensation  for  wear  of  either 
the  casing  or  cylinder  being  provided  by  a  slot  in  the  casing.  Contrac- 
tion and  expansion  of  the  casing  is  controlled  by  screws  C  and  D.  To 
contract  the  casing  loosen  the  screws  in  top  bracket  E,  turn  screw  C  to 
the  left,  and  screw  D  to  the  right.  When  proper  adjustment  is  secured 
turn  screw  C  to  the  right.  To  expand  the  casing  turn  screw  D  to  the 
left,  then  screw  C  to  the  right,  after  which  screw  D  to  the  right.  Longi- 
tudinally the  cylinder  is  held  in  position  in  the  cylinder  casing  by  a  flange 
on  the  cylinder  and  adjustable  clips  F.  When  the  cylinder  is  indexed 
by  the  segment  gear  G,  Figs.  78  and  82,  it  is  brought  into  correct  position 
by  plunger  M,  Fig.  82.  When  in  proper  alinement  adjusting  screw  A^, 
Fig.  82,  is  resting  upon  half-round  plunger  P.  Plunger  M  is  designed  to 
enter  only  a  short  distance  into  bushing  R,  the  tapered  portion  of  the 
plunger  striking  the  upper  wall  which,  with  the  assistance  of  springs  S, 
insures  perfect  contact  between  adjusting  screw  A'^  and  half-round  plun- 
ger P. 

WORK    SPINDLES,    BEARINGS,    ETC. 

The  work  spindles  are  of  steel,  chucks  of  the  push  type  being  used. 
Each  nose  piece  is  ground  in  place  on  its  spindle.  Bronze  parallel  bear- 
ings are  used  in  the  cylinder.  The  front  and  rear  tapered  bearings  are 
of  bronze,  both  running  in  hardened  and  ground  steel  bushings.  The 
longitudinal  movement  of  the  spindles  is  adjusted  for  end  play  by  turning 
collars  A^,  Fig.  83.  To  adjust  the  chucks  to  the  rods,  finger-holder  0, 
Fig.  83,  should  be  turned  to  the  right  (after  first  unscrewing  the  set  screw) 
if  it  is  desired  that  the  chucks  grip  the  stock  tighter,  or  if  less  tightly,  to 
the  left,  the  set  screws  being  tightened  after  the  proper  adjustment  has 
been  secured.  The  feed  chucks  are  threaded  to  turn  right-handed  and 
fit  closely  in  the  feed  tubes  to  prevent  their  coming  loose  when  the 
machine  is  in  operation.  As  the  work  spindles  rotate  to  the  left  the  nose 
pieces  have  left-hand  threads. 


WORK    SPIXDLKS,    BEARIXCS,    ETC. 


101 


Fig.  S2.  —  Iiulexin";  and  Lockino;  Mechanism 


Fiti.  S.S.  —  Spindle  Constructiun 


102      THE   ACME   MULTIPLE-SPINDLE   Al'TOMATIC   SCREW    MACHINE 


FRICTIONS 

The  spindle  frictions,  Fig.  83,  which  make  it  possible  to  hold  one  work 
spindle  stationary  while  the  remaining  three  continue  to  rotate,  are  made 
up  of  four  princii^al  parts,  viz.:  sleeve  .1;  male  tapered  section  and  gear 
B;  female  tapered  section  C;  spring  seat  D.  The  work  spindles  as 
already  stated  are  driven  by  a  gear  attached  to  the  spindle-driving  shaft 
meshing  with  the  geared  portion  of  the  male  tapered  section  B,  engaging 
female  tapered  section  C,  which  is  keyed  to  sleeve  A;  sleeve  ^i  being 
keyed  to  the  work  spindle,  b'ections  B  and  C  are  held  in  engagement  by 
springs  E.  When  sections  B  and  C  are  not  engaged,  section  B  not  being 
keyed  to  sleeve  A  rotates  freely  on  it,  and  section  C,  sleeve  A,  and  the 
work  spindle  remain  stationary.  Disengagement  of  members  B  and  C 
resulting  in  the  work  spindle  being  held  stationary  is  necessary,  while 
threading,  cross-drilling,  side  milling,  or  other  special  operations  of  this 
nature  are  being  performed.  Where  the  friction  caused  by  lever  F  com- 
pressing springs  E  is  insufficient  to  hold  the  work  sphidle  stationary, 
which  may  be  the  case  when  cutting  coarse  threads,  adjustable  plunger 
G  located  on  the  under  side  of  bracket  L  (which  bracket  is  attached  to 
the  cylinder  casing)  is  brought  into  contact  with  lug  M  inserted  in  sec- 
tion C  of  the  friction.  This  will  prevent  rotation  of  the  work  spindle 
during  the  threading  operation.  The  length  of  time  the  work  spindle 
must  be  held  stationary  is  determined  by  the  duration  of  the  threading 
or  special  operations.  The  opening  and  closing  of  the  friction  is  con- 
trohed  by  cams  on  cam  drum  G,  Fig.  79,  operating  through  a  roll,  lever 
A,  and  a  toggle-locking  device.  The  opening  cam  is  positive,  while  the 
closing  cam  is  adjustable  on  the  cam  drum.  In  the  larger  machines 
positive  clutches  are  used  in  place  of  frictions  to  provide  against  slip- 
ping; these  are  operated  in  the  same  manner  as  the  frictions  on  the  smaller 
machines. 

MAIN   TOOL    SLIDE 

The  main  tool  slide,  Fig.  84,  carries  the  tools  usually  carried  in  the 
turret  of  single-spindle  machines,  i.e.,  those  worked  from  the  end.  Four 
is  the  maximum  number  of  tools  it  will  accommodate,  although  by  the 
use  of  combination  tools  in  these  positions,  more  than  four  operations 
may  frequently  be  performed.  The  locations  of  the  several  tools  are 
designated  as  "positions."  The  first  is  the  position  from  which  the  tools 
engage  the  bar  on  which  the  forming  tool  is  operating.  The  second, 
that  above  and  vertically  parallel  to  the  first  position;  the  third,  opposite 
to  and  horizontally  parallel  to  the  second  position;  the  fourth,  below 
and  vertically  parallel  to  the  third  position. 

The  tool  slide  is  moved  toward  and  from  the  work  by  cams  bolted 


MAIN   TOOL   SLIDE 


103 


to  cam  drum  xi,  Fig.  84,  operating  on  a  roll  attached  to  adjustable  slide 
B,  which  is  bolted  to  the  body  of  the  main  tool  slide. 

It  is  good  practice  to  have  the  shanks  of  tools  extend  as  far  back  in 
the  tool  spindles  as  possible  in  order  to  secure  increased  rigidity.  To 
make  this  possible  two  methods  of  adjustment  are  provided  when  chang- 
ing from  long  to  short  work  and  vice  versa,  viz.,  the  changing  of  the  posi- 
tion of  the  lead  cam  on  the  cam  drum,  also  that  of  adjustable  slide  B, 
Fijr.  Si. 


l''iu.  84.  —  .Main  Tuul  Slide 


When  it  is  necessary  to  pci'form  an  operation  from  the  fourth  posi- 
tion in  the  tool  slide,  about  4  niches  should  be  taken  off  the  wide  end  of 
the  lead  cam  on  Nos.  53  to  56  machines  inclusive,  and  about  3  inches  on 
the  Nos.  51  to  52  machines.  This  is  done  to  allow  the  tool  in  this  posi- 
tion to  clear  the  work  before  the  piece  is  cut  off. 

If  desirable,  the  tool  spindle  in  the  second  position  can  be  rotated  by 
means  of  the  gears  driven  by  the  sliding  gear  keyed  to  the  spindle-driving 
siiaft  for  driving  the  thi-eading  spindle.  The  back  plate  attached  to  the 
rear  of  the  vertical  portion  of  the  tool  slide  with  screws  and  spacing  collars 
carries  a  stud   u})oii    which   tlie   intermediate  goar  that   drives  the    tool 


104      THE   ACME   MULTIPLE-SPIXDLE   AUTOMATIC   SCREW    MACHINE 

spindle  in  this  position  rotates.  This  spindle  may  be  driven  by  loosen- 
ing a  collar  at  the  rear  sufficiently  to  allow  it  to  rotate  freely,  unscrewing 
a  nut  on  the  stud  and  moving  the  stud  sufficiently  to  bring  the  interme- 
diate gear  into  mesh  with  the  gears  on  the  spindle-driving  shaft,  then 
tightening  the  stud  again  by  screwing  up  the  nut.  The  rotation  of  the 
second  position  tool  spindle  is  found  very  convenient  in  cases  where  a 
very  small  hole  is  to  be  drilled.  Screws  are  provided  for  use  in  adjusting 
the  position  of  the  individual  tools  in  the  tool  slide  and  also  serve  as  a 
gage  stop  in  re-setting  tools  in  their  original  positions  after  they  have 
been  removed  from  the  slide. 

THREADING    MECHANISM 

The  threading  mechanism  is  so  constructed  as  to  allow  for  the  thread- 
ing operation  as  much  time  as  is  consumed  in  the  longest  milling,  drill- 
ing, or  forming  operation,  thus  insuring  good  threads,  and  long  life  for 
the  threading  tools. 

Oil  is  forced  through  the  die  spindle  into  the  die  from  the  rear,  thus 
providing  ample  lubrication.  The  die  spindle  is  rotated  by  means  of 
sliding  gear  E,  Fig.  85,  which  is  keyed  to  and  driven  by  the  top  shaft. 


Fig.  85.  —  Speed  Change  Gear  for  Threading  Spindle 

When  the  die  spindle  is  not  in  use  clip  F  can  be  raised  and  the  gear  slipped 
out  of  mesh  with  the  threading-spindle  gears.  When  clip  F  is  in  engage- 
ment with  the  groove  nearest  the  teeth  in  gear  E  the  threading  spindle 
sleeve  will  be  driven  direct  and  at  its  highest  rate  of  speed.  When  clip 
F  is  in  engagement  with  the  groove  farthest  from  the  teeth  in  gear  E 
the  sleeve  will  be  driven  through  the  intermediate  and  compound  gears 
G  and  H  at  its  lowest  rate  of  speed.  The  threading-spindle  sleeve  rotates 
about  seven  times  as  rapidly  when  driven  direct  as  when  driven  through 
intermediate  and  compound  gears.  In  threading  brass  or  cutting  very 
fine  threads  on  soft  steel,  the  direct  drive  may  be  used.  In  most  other 
cases  it  is  advisable  to  use  the  intermediate  drive. 

The  threading  spindle  is  driven  by  pins  A,  Fig.  86,  attached  to  the 
threading-spindle  sleeve,  engaging  pin  B  in  the  spindle.     Pin  B  is  adjust- 


THREADING   MECHAN ISM 


105 


able  for  length,  this  adjiJ^tment  being  used  when  the  pitch  of  the  thread 
is  such  that  the  forward  travel  of  the  tool  must  be  faster  than  that  of 
the  tool  slide.  These  pins  are  furnished  in  various  lengths.  AVhen  the 
tool  becomes  slightly  dulled,  or  when  the  die  has  a  shallow  throat  (which 
is  necessary  when  the  thread  is  to  be  cut  close  up  to  the  head  or  shoulder 
of  the  work),  the  device  in  Fig.  86  is  brought  into  use.  This  is  known 
as  the  thread  starter  and  operates  as  follows. 


Fig.  8(3.  —  Threadinsi;  Mechanism 

At  the  time  the  tool  is  in  position  where  it  just  touches  the  end  of  the 
blank  to  be  threaded,  roll  D  should  be  adjusted  so  as  to  be  brought  into 
contact  with  swinging  pawl  E,  the  roll  holder  being  adjustable  on  rod 
F,  which  is  operated  by  an  adjustable  cam  on  cam  drum  B  (Fig.  79), 
through  lever  G,  Fig.  86.  Spring  H  compensates  for  any  slight  variation 
there  nuiy  be  in  the  length  of  the  blank,  making  the  starting  of  the  tool 
positive,  but  the  operation  of  the  mechanism  flexible.  End  play  in  the 
threading-spindle  sleeve  is  taken  up  by  collars  L. 

After  the  tool  has  completed  the  operation  of  threading,  the  work 
spindle  is  released  (as  explained  in  connection  with  the  operation  of  the 
frictions)  and  the  tool  runs  off  when  the  ratchet  A'  on  the  rear  end  of  the 
die  spindle  engages  flexible  pawl  M,  all  receding  with  the  tool  slide.  In 
setting  tools  for  threading,  before  starting  the  machine  the  ratchet  should 
clear  flexible  pawl  M  from  J,  to  f\  inch  when  pins  .1  and  B  on  the  threading- 
spindle  sleeve  and  spindle  are  placed  end  to  end.  With  the  regular 
threading  mechanism  only  right-hand  threads  can  be  cut,  but  the  machine 
can  be  equipped  with  left-hand  threading  attachment  when  so  desired. 


106      THE   ACME   xMULTIPLE-SPINDLE   AUTOMATIC   SCREW   MACHINE 
FORMIXG    AND    CUTTING-OFF    SLIDES 

These  slides  are  made  adjustable  for  position  lengthwise  of  the  ma- 
chine. This  makes  it  possible  to  change  the  longitudinal  position  of  the 
cutting-off  and  forming  tools  without  disturbing  the  tools  themselves. 
The  cutting-off  tool  when  of  the  blade  variety  is  adjustable  for  hight  by 
means  of  a  screw  in  the  slide.  A  gage  for  setting  the  forming  tool  to  the 
proper  hight  is  furnished  with  each  machine. 

On  machines  Nos.  52,  55,  and  56  both  the  levers  which  operate  the 
forming  and  cut-off  slides  H.  Figs.  78  and  79,  and  the  bracket  in  which 
they  are  pivoted,  are  drilled  in  two  separate  locations.  This  double 
drilling  makes  it  possible  to  form  deeper  and  cut  off  larger  diameters  of 
stock  when  the  levers  are  pivoted  in  the  lower  holes  without  substituting 
cams  of  a  greater  throw  or  travel,  as  designated  in  a  table  accompanying 
the  machine. 

TOP    SLIDES 

Two  of  these  slides  are  provided,  operating  in  second  and  third 
positions  as  represented  in  Figs.  78  and  79.  They  are  adjustable  length- 
wise of  the  machine  and  are  used  for  nurling,  thread-rolling,  shaving, 
light  forming,  etc.,  and  are  very  useful  in  producing  man}'  varieties 
of  work.  Their  operation  is  pro^•ided  for  through  bar  cams  attached 
to  the  tool  slide.  Cam  il/.  Fig.  79,  moves  the  top  slide  toward,  and  cam 
A'^  from  the  work.  These  cams  can  be  readily  filed  to  any  angle,  thus 
providing  whatever  feeds  may  be  deemed  desh-able  for  the  tools  in  use. 
In  operating  tools  in  these  top  slides,  care  must  be  exercised  in  having 
cam  M  notched  and  the  tools  so  set  that  the  slides  will  be  in  their  orig- 
inal position  and  the  tools  out  of  the  way  before  the  indexing  of  the 
cylinder  carr^-ing  the  work  spindles  takes  place. 

The  cams  rarely  need  changing  as  the  set  provided  with  the  machine 
covers  a  wide  range  of  work;  extreme  cases,  however,  require  a  faster  or 
a  slower  feed. 

TOOLS    AND    ATTACHMENTS 

Fig.  87  illustrates  the  machine  as  it  appears  equipped  with  tools  for 
each  position  for  operation  on  four  rods  at  the  same  time.  Fig.  88  is  a 
group  of  collets,  feed  chucks,  and  jaws.  Fig.  89  illustrates  various  types 
of  box  tools  with  back  rest  jaws,  roller  rests,  etc.  Fig.  90  shows  die, 
tap  and  drill  holders  with  button  dies,  tap  and  drill  bushings,  die  exten- 
sions, etc.  The  die  holder  at  the  top  of  the  group  is  a  telescopic  device 
used  in  cutting  two  threads.  A  tap  is  frequently  used  in  place  of  the 
second  die.  At  the  center  and  left  of  the  group  is  a  friction  die  holder 
used  for  threading  close  to  a  shoulder  on  small  work;  a  button  die  holder 
and  extension  being  shown  just  to  the  right. 

Fig.  91  is  a  set  of  tools  for  machining  a  stud  shown  at  the  center  of 


TOOL?;    AND    ATTACHMEXT^ 


107 


nd  Tool  Positions 


the  group.  As  this  work  is  indexed  through  the  four  positions,  the  tools 
operate  as  follows:  Forming  tool  and  lower  box  tool  in  the  first  position; 
shaving  tool  and  box  tool  with  roller  rest,  second  position;  die  in  the  third 
and  cut-off  tool  in  the  fourth  position.  The  shaving  tool  shown  just 
above  the  die  is  similar  to  a  number  shown  in  Fig.  92,  which  also  includes 
several  types  of  nurls,  and  a  thread-rolling  tool.  The  shaving  tool  is 
mounted  in  the  machine  as  illustrated  in  Fig.  93.  It  consists  of  a  holder 
carrying  a  rest  and  a  shaving  blade,  the  holder  being  pivoted  to  allow 


Tic;.  88.  • —  Spring-Collets  and  Feed  Chucks 


108       THE    ACME    MULTIPLE  SPINDLE    AUTOMATIC    SCREW    MACHINE 


UiG.  89.  —  Box  Tools  of  Various  Types 

the  blade  and  rest  to  find  their  own  center.  As  the  distance  between 
blade  and  rest  when  once  set  is  positive,  and  as  the  tool  is  allowed  to  find 
its  own  center,  it  produces  very  accurate  results. 


Fig.  90.  —  Die,  Tap  and  Drill  Holders 


TOOLS    AND    ATIWCHMENTS 


109 


I'k;.  91.  —  Set  of  Tools  for  Machining  a  Stud 

The  thread-rolling  tool  mounted  as  shown  in  Figs.  93  and  94  is  espe- 
cially adapted  for  rolling  a  thread  at  the  back  of  a  shoulder.  It  consists 
of  a  thread  roller  mounted  in  a  holder  which  is  secured  in  the  rear  top 


Fig    92.  ■ —  Sliavinp,  Tliicad  RDllins;,  and  Nurlinfj  Tool.- 


110       THE    ACME    MULTIPLE-SPINDLE    AUTOMATIC    SCREW    MACHINE 

slide.  It  produces  smooth,  accurate  threads  and  is  obviously  appli- 
cable to  many  cases  where  a  die  cannot  be  operated.  At  the  same  time 
it  may  be  used  satisfactorily  at  the  front  side  of  a  shoulder  where  ordi- 
narily a  die  would  be  employed.     Fig.  94,  which  is  a  rear  view,  shows  a 


Jg 

^^MP^ 

^^^ 

^3t^ 

a^  '^A/^^Ki 

^sKf 

^^^%^^^^^H 

•^P 

Fig.  93.  —  Shaving  and  Thread-Rolling  Tools  in  Position 


Fig.  94.  — Work  Before  and  After  Thread- 
ing with  Roller 


piece  of  work  before  and  after  threading  and  clearly  illustrates  the  manner 
in  which  the  threading  roll  can  be  applied  between  a  shoulder  on  the 
work  and  the  face  of  the  chuck. 


M I L r,IX( ;    ATTAfH.MEXT; 


111 


CROSS-DRILLIXG    ATTACHMEXTS 

The  cross-di'illiiip;  attachment  shown  in  Fig.  V)o  is  operated  in  the  third 
position,  where  prcnision  is  made  for  stopping  the  rotation  of  the  stock 
to  aUow  for  threading  and  other  operations.  The  attachment  is  secured 
to  the  cut  ting-off  slide  and  actuated  by  the  cutting-off  lever.  On  the 
larger  sizes  of  machines  sufficient  feed  for  the  drill  is  obtained  by  an  aux- 
iliary lever  at  the  side  of  the  attachment,  -which  increases  the  throw 
of  the  cam.  Adjustments  are  provided  for  governing  the  depth  and  posi- 
tion of  the  hole  in  the  work.  The  drill  spindle  is  operated  by  a  b?lt  from 
a  countershaft.  By  using  a  combination  tool  it  is  possible  to  drill  and 
countersink  a  hole  at  the  same  time. 


Fig.  9.5.  —  Cross-Drilling  Attafhinent 

Cross  drilling  from  the  top  of  the  piece  may  be  accomplished  by  means 
of  an  attachment  used  in  place  of  the  top  slide  over  the  third  position. 
This  attachment  may  also  be  used  in  conjunction  with  the  one  on  the 
cutting-off  slide,  the  holes  being  drilled  at  a  given  angle  to  each  other. 
Also,  when  required,  the  machine  may  be  modified  to  allow  the  two  holes 
to  be  positioned  at  any  angle  with  each  other  between  90  degrees  and  a 
few  degrees  from  parallel. 


MILLIXU    ATTACHMEXTS 

There  are  two  forms  of  end  milling  attachments  for  the  machine,  one 
being  driven  by  bolt;  tiie  otiier  l)y  gears.  The  latter  type  is  illustrated 
in  Fig.  U6,  and  is  adapted  to  the  iioavier  classes  of  work;  for  example, 


112       THE    ACME    MULTIPLE -SPINDLE    AUTOMATIC    SCREW    MACHINE 

where  two  cutters  are  required.  Tliese  attachments  are  operated  from 
the  main  tool  slide,  opposite  the  third  stock  position  owing  to  the  neces- 
sity of  having  the  stock  stationary  during  the  drilling  operation.     Either 


Fig.  96.  —  End-Millino;  Attachment 


attachment  can  be  used  in  conjunction  with  cross-drilling  or  side-milling 
attachments,  but  are  not  applicable  where  threading  operations  are  re- 
quired as  their  position  on  the  machine  is  then  occupied  by  the  threading 
spindle. 


Fig.  97. 


Side-Milling  Attachment 


A  side-milling  attachment  is  shown  mounted  on  the  cross  slide  in 
Fig.  97;  and  in  Fig.  98  a  slotting  attachment  is  illustrated,  the  work 
handled  in  this  device  being  received  from  the  spindle  by  a  turret  holder 
and  carried  around  in  front  of  the  saw  or  saws  as  the  case  may  be.  After 
the  operation  the  piece  is  ejected  in  the  manner  indicated. 


MACHINE    SIZES 


113 


Fig.  98.  —  Slulling;  ami  Milling  Attachment 
MACHINE    SIZES 

A  setting-up  print  for  the  different  sizes  of  Acme  machines  is  repro- 
duced to  small  scale  in  Fig.  99  with  the  leading  over-all  dimensions,  belt 
widths,  etc.  The  several  sizes  in  which  the  machine  is  built  range  from 
a  chuck  capacity  of  ^-inch  and  feed  length  of  2^  inches  to  a  chuck  capac- 
ity of  2^  inches  and  feed  length  of  10^  inches. 


V-K--5 


Uk).Im 

B.r.^ 

Sa.nb.. 

A 

B 

c 

D 

E 

F 

G 

u 

I 

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30 

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1 

Fii;.  It'.t.  —  ()\c'iluail  Works  and  Overall  Dimensions  Acme  Automatic  Screw  Machine 


CHAPTER  XII 

The  Universal  Multiple-Spindle  Automatic  Screw  Machine 

The  general  design  of  this  machine,  which  is  built  by  the  Tniversal 
Machine  Screw  Company,  Hartford,  Conn.,  is  well  shown  in  the  front 
and  rear  views,  Figs.  100  and  101. 


Fig.   lOU.  —  Universal  Multiple-Spindle  Automatic  Screw  Machine 

The  machine  has  five  spindles  and  is  operated  from  the  countershaft 
by  a  single  belt  passing  over  the  plain  driving  pulley  shown  at  A,  Fig. 
102.  The  five  spindles  are  carried  in  a  cylinder  which  is  indexed  to  bring 
one  spindle  after  another  in  front  of  each  of  the  five  tools  in  the  tool 
slide.  The  latter  is  fed  forward  by  the  cam  underneath,  bringing  all 
the  tools  into  action  sinmltaneously,  and  a  piece  is  completed  at  each 
advance  of  the  tool  slide. 

114 


OPEHATIOX   OF  THE  SPIXDLES 


115 


opp:ration  of  the  spindles 

For  ordinary  turning,  forming,  drilling,  and  other  operations,  the 
spindles  run  in  a  left-hand  direction;  for  threading,  the  sjjindle  with  the 
work  is  run  slowly  to  the  rigiit  during  the  operation  and  upon  the  die 
reaching  the  proper  distance  the  spindle  is  reversed  and  the  die  rapidly 
drawn  ofif  the  work.  As  will  be  seen,  each  spindle  has  at  its  rear  end 
two  spur  gears.  The  one  nearest  the  turret  is  operated  by  a  gear  on  a 
centi'id  sleeve  passing  thi'ough  tiie  turret  and  supported  at  its  right-hand 


li(i.    Kll.        I'liivcrsal  .Multiiilc-Spiiidlc  Automatic  Screw  .Mncliiiic  (Hear  \'ic\v  . 

end  as  shown  at  B,  Fig.  102.  the  gears  C  and  D  serving  to  drive  this  sleeve 
or  hollow  shaft,  thiough  which  pas.ses  shaft  E.  This  latter  shaft  carries 
at  its  left  end  gearing  engaging  the  outer  gears  on  the  spindles  for  driving 
them  during  threading  oi)erations.  The  drive  for  shaft  K  is  transmitted 
through  the  medium  of  change  gears  in  train  F  at  the  outer  end,  connect- 
ing with  the  right-hand  end  of  the  short  driving  shaft  G.  It  is  obvious 
that  by  the  series  of  change  gears  suitable  si)indle  s])eeds  for  threading 
may  always  be  ()l)taine(l.     An   impoi'tant   featui-e   in  this  spindle-driving 


116     rXIVERSAL   MULTIPLE-SPIXDLE    AUTOMATIC   SCREW   MACHINE 

mechanism  is  a  positive  type  of  clutch  (operated  by  an  arm  at  the  rear) 
for  connecting  the  spindles  with  either  the  left-hand  turning  or  right- 
hand  threadins;  motion. 


THE    CAM-SHAFT    DRIVE 

The  cam  shaft  is  also  driven  from  short  shaft  G,  Fig.  102.  This  shaft 
by  means  of  bevel  gears  H  drives  shaft  /  upon  which  is  mounted  freely 
pulley  J.  which  may  be  secured  to  /  by  operating  lever  K  and  so  engaging 
the  conical  clutch  with  the  pulley.  This  pulley  is  belted  to  the  pulleys 
below  for  driving  the  cam-shaft  gearing,  the  arrangement  of  which  is 
shown  clearly  in  Fig.  103.  and  when  the  lever  K,  Fig.  102,  is  moved  to 
the  right  the  friction  clutch  in  J  is  disengaged  and  a  brake  L  applied  to 
the  pulley,  stopping  it  and  the  cam  shaft  instantly. 


e3:::::l::- 


Fig.  102.  —  Dri\'ing  Mechanism  of  Universal  Automatic  Screw  Machine 

This  is  a  convenience  especially  when  setting  up  for  a  piece  of  work 
as  the  feed  motion  may  be  started  and  stopped  at  will  without  stopping 
the  spindle. 

Of  the  two  pulleys  placed  side  by  side  as  in  Fig.  103.  on  the  worm  shaft 
for  operating  the  cam-drum  shaft,  the  outer  one  drives  the  worm  shaft 
direct  for  rapid  traverse  of  the  tools  during  idle  or  non-cutting  movements, 
while  the  inner  one  drives  the  shaft  through  change  gearing,  by  which 
the  recjuisite  rate  of  feed  is  always  readily  obtainable.  The  short  belt 
is  of  course  automatically  shifted  from  one  pulley  to  the  other  during 


THE   LOCKING    BOLT   FOR   THE   SPL\DLE   TURRIOT 


117 


the  cycle  of  operations;  the  shifter  lever  and  dogs  for  contr()lliii<r  it  Ix'ing 
plainly  seen  in  Figs.  101  and  103.  The  outer  end  of  the  worm  shaft  is 
squared  to  receive  a  crank  handle  wiiich  facilitates  hand  operations  of  the 
cam  shaft  dui'ing  the  setting-up  process. 


Tk;.  1():{. 


-  Mi'C'liaiiisin  for  Opcratiiii;  Cain  Siialt   of  Uni- 
versal  Automatic  Screw  Machine 


THE    LOCKIXG    nOLT    FOR    THE    SPIXDLE    TURRET 

The  turret-locking  holt  is  shown  in  Fig.  104  and  needs  little  descrip- 
tion, as  its  general  form  and  mode  of  operation  are  indicated  in  this 
engraving  and  the  half-tone,  Fig.  101.  This  latter  view  also  shows  in 
conjunction  with  the  front  view,  Fig.  100,  the  method  of  operating  the 


118     UNI\'ERSAL   MULTIPLE-SPINDLE   AUTOMATIC   SCREA\'   ^L\CHINE 

three  independent  cross  slides,  the  arrangement  of  oil  pump  and  piping, 
and  the  gearing  by  which  the  pump  is  positively  driven  from  the  large 
spindle-driving  gear  represented  at  D,  Fig.  102.  The  countershaft  is  a 
single-speed  affair  fitted  with  tight  and  loose  pulleys. 


Fig.   104.  —  Locking  Bolt  Detail 


This  macliine  is  known  as  the  No.  3  and  takes  work  up  to  H  inches 
in  diameter,  feeds  lengths  up  to  6  inches,  and  machines  a  maximum  length 
of  5  inches.  Two  smaller  sizes  take  work  |  and  f  inch  diameter  respec- 
tively. 


C'HAITEU   XIII 

The  Gridley  MiLTiPLf>.SrixDLE  Aitomatic  Tlrhet  Lathe 

In  the  accompanyino;  engravings  is  illustrated  the  (liidley  multi])le- 
spiiulle  automatic  turret  lathe  built  by  the  Windsor  Machine  Company. 
The  single-spindle  automatic  built  by  this  concern  is  illustrated  in  Chapter 

vn. 

The  four-spindle  machine  forming  the  subject  of  the  present  chapter 
is  well  illustrated  bv  tiie  general  views.  Figs.  105.  106.  and  107:  its  con- 


I'lc.   lO.j.  — Gridley  Maltiple-.'^piiKlle  Autoniatic  Turret  L;itlie 

struction  will  be  understood  by  referring  to  these  half-tones  and  to  the 
details  presented  in  the  line  drawings.  Like  the  single-spindle  machine 
referred  to,  this  automatic  has  a  four-sided  slide  far  carrying  the  "  tur- 
ret" tools;   the  tool  slide  in  this  ease,  however,  is  not  rotated  to  bring 

119 


120      THE   GRIDLEY   MULTIPLE-SPINDLE    AUTOMATIC   TURRET   LATHE 

the  tools  one  after  another  into  position  for  the  successive  cuts,  as  the 
four  spindles  themselves  are  carried  in  a  cylinder  that  is  indexed  step  by 
step  to  bring  each  spindle  successively  into  position  for  the  bars  of  stock 
to  be  operated  upon  by  the  various  tools. 

All  of  tlie  tools  held  by  the  tool  slide  are  fed  forward  together,  one  tool 
rough-turning  the  ]:)ar  in  one  spindle,  another  tool  taking  a  finishing  chip 
on  the  piece  held  in  the  next  spindle,  a  die  threading  the  piece  in  the 
next  spindle,  and   the  finished   piece   being  cut  off  and  a  new  length  of 


-*:?\ 


Fig.   106.  —  Gridley  Multiple-Spindle  Automatic  Turret  Lathe  (Rear  \'ie\vj 

stock  fed  through  the  chuck  at  the  fourth  position  of  the  spindle,  or  such 
other  operations  being  performed  as  the  piece  may  require.  As  all  of 
these  operations  are  performed  simultaneously,  it  will  be  seen  that  the 
time  to  make  a  completely  finished  piece  and  cut  it  off  will  be  only  the 
time  required  to  perform  the  longest  operation  plus  the  time  required  to 
return  the  tool  slide,  revolve  the  spindle  cylinder,  and  move  the  tools 
back  to  their  cutting  position. 


THE    SPINDLE    AND    TOOL    SLIDE 


The  spindles,  their  carrying  cylinder,  and  the  tool  slide  are  shown  in 
Fig.  107  removed  bodily  from  the  machine;  this  half-tone  reveals  also  a 
number  of  other  interesting  features  of  construction.  A  horizontal  sec- 
tion through  one  of  the  spindles  is  given  in  Fig.  108,  and  it  will  be  noticed 


THE   SPIXDLE  AND   TOOL   SLIDE 


121 


that  the  spindle  takes  a  long,  straight  bearing  in  a  lumen-bronze  sleeve 
which  admits  of  ready  renewal  as  a  whole  in  the  event  of  sufficient  wear 
occurring  to  make  this  necessary.  The  hub  of  the  cylinder  around  which 
the  four  spindles  are  located  is  extended,  as  represented  in  Fig.  105,  to 
form  a  long  bearing  for  the  tool  slide,  this  feature  of  mounting  spindles 
and  tool  slide  on  the  same  member  having  been  adopted  in  conjunction 
with  the  feature  of  large  bearing  areas  to  insure  permanent  alinement  of 
spindles  and  tools.  The  bearings  of  the  spindle-carrying  cylinder  are 
on  the  large  diameters  .1  and./^.  Fig.  107.  In  the  event  of  any  wear  taking 
place  between  these  surfaces  at  either  end  and  the  bearings  formed  in 
the  main  frame  of  the  machine,  the  alinement  of  spindles  and  tool  slide 
need  not  bo  affected,  as  l^oth  will  simply  move  together. 


Fig.   107.  —  Gridley  Multiple-Spindle  Automatic  Turret  Lathe  with  Spindles  and  Tool 

Slides  Removed 

In  addition  to  the  features  ju.st  described,  Figs.  105  and  107  show 
clearly  the  method  of  preventing  the  tool  slide  from  rotating,  the  arrange- 
ment consisting  of  an  arm  attached  to  the  tool  slide  and  machined  at 
the  outer  end  to  fit  a  longitudinal  guide  bar  located  as  represented  at 
the  top  of  the  machine. 

The  spindles  have  the  usual  collets  and  stock-feed  device,  and  are 
driven  by  the  pulley  shown  at  the  right-hand  end  of  the  machine  in  Fig. 


122      THE   GRIDLEY   MULTIPLE-SPINDLE   AUTOMATIC   TURRET   LATHE 

105.  This  pulley  is  keyed  to  one  end  of  a  driving  shaft  running  through 
the  center  of  the  spindle-carrying  cylinder  as  in  Fig.  108,  and  carrying 
on  its  other  end  a  gear  meshing  with  a  gear  keyed  on  each  of  the  spindles 
at  the  rear  end  of  the  bearing.  The  spindles  are  run  constantly  in  one 
direction  without  stopping  or  reversing  for  the  purpose  of  threading, 
that  operation  being  taken  care  of  by  the  threading  mechanism  to  be 
referred  to  later. 


Fig.  lOS.  —  Spindle  Construction 


OPERATION    OF   THE    TOOL    SLIDE 

The  cam  shaft  C,  Figs.  107  and  109,  carries  the  cams  for  operating 
the  tool  slide  and  the  forming  and  cutting-off  tools;  the  cams  for  operat- 
ing the  chuck  and  feeding  the  stock;  and  the  mechanism  for  revolving 
the  cylinder.  It  is  driven  at  two  speeds,  one  of  which  is  comparatively 
slow  for  use  during  the  time  the  tools  are  cutting,  the  other  a  high  speed, 
for  returning  the  tool  slide  and  revolving  the  spindle  cylinder.  During 
the  slow  movement  (while  the  tools  are  cutting)  it  is  driven  by  a  worm  D, 
Fig.  109,  on  the  spindle-driving  shaft,  through  the  change-gear  box  E, 
worm  shaft  F  and  worm  gear  G  keyed  on  cam  shaft  ('.  When  the  tools 
have  finished  cutting,  the  loose  pulley  H,  which  runs  at  a  constant  speed, 
is  clutched  to  the  worm  shaft  F.  The  drawing  shows  a  toothed  clutch 
for  this  connection,  but  a  friction  is  now  used  instead.  This  method  of 
driving  the  cam  shaft  gives  a  c^uick  change  feed  for  the  cutting  tools  and  a 
constant  maximum  speed  for  what  are  termed  "idle  movements,"  irre- 
spective of  the  rate  of  speed  during  the  cutting  period.  The  quick-change 
gears  in  the  feed  box  E  are  controlled  by  two  handles,  the  lower  one  / 
having  three  locations,  corresponding  to  the  feed  cam  used,  there  being 


TURNING   AND   THREADING   APPARATUS 


123 


three  of  these  cams  furnished,  one  for  work  not  over  2  inches  long,  one 
for  work  between  2  and  4  inches  and  the  other  for  work  ranging  between 
4  and  6  inches  in  length.  Although  the  6-inch  cam  can  be  used  for  the 
shortest  work,  there  is  of  course  an  appreciable  loss  of  time  in  moving 
the  tool  slide  its  full  travel  when  working  short  pieces.     When  the  lower 


Fig.   109.  —  Feod-Driving  Mechanism 

handle  is  in  the  position  corresponding  to  the  feed  cam  which  is  being  used, 
the  upper  handle  J  can  be  placed  in  any  one  of  the  six  positions  to 
give  the  feed  desired,  the  figures  75,  100,  125,  150,  175  and  200  represent- 
ing the  revolutions  of  the  .spindle  to  one  inch  of  travel  of  the  tool  sliile. 

TURMXC    AND    THREADING    ATPAKATUS 

The  form  of  tool  slide  allows  a  tuiiiing  tool  to  be  used  identical  with 
that  employed  on  the  (iridley  single-spindle  automatic  turret  lathe. 
The  tool  sliile  has  sufficient  room  to  allow  of  one  tool  l^eing  placed  back 
of  another. 

As  the  spindles  are  driven  constantly  in  one  direction,  as  stated  above, 
and  in  order  that  a  high  cutting  speed  for  the  turning  tools  and  a  low 
cutting  speed  for  the  tlie  can  ])e  used,  it  is  necessary  to  rotate  the  die 


124     THE  GRIDLEY  MUTIPLE-SPINDLE  AUTOMATIC  TURRET  LATHE 

at  a  speed  slightly  less  than  the  speed  of  the  spindle  while  threading, 
and  at  a  higher  speed  when  running  the  die  off  the  piece.  This  is  accom- 
plished by  means  of  two  gears  on  the  spindle-driving  shaft,  these  gears 
meshing  with  two  loose  gears  on  the  threading  shaft,  vrhich  in  Figs.  105 
and  106  is  shown  immediately  above  and  to  the  rear  of  the  tool  slide. 
These  gears  are  of  such  ratio  that  when  one  of  them  is  clutched  to  the 
die  shaft  it  will  rotate  the  die  at  a  speed  slightly  less  than  that  of  the 
spindle;  when  the  other  gear  is  clutched  to  the  shaft,  the  die  will  rotate 
at  a  higher  speed  so  as  to  run  off.  When  a  left-hand  thread  is  being 
cut,  the  die  rotates  faster  than  the  spindle  during  the  threading  opera- 
tion and  slower  when  running  off. 


Fig.   110.  —  Cylinder  Revolving  and  Locking  Mechanism 


THE    INDEXING    MECHANISM 

The  mechanism  for  revolving  the  spindle  cylinder  is  illustrated  by 
Fig.  110,  which  also  shows  the  method  of  operating  the  locking  bolt. 
Arm  K  mounted  on  the  cam  shaft  carries  a  cam  L  for  withdrawing  the 
locking  bolt  M  and  has  at  its  inner  end  a  roll  which  at  each  revolution 
of  the  arm  enters  the  channel  in  the  face  of  the  cylinder  flange  and  rotates 
the  cylinder  one  quarter  turn,  the  locking  bolt  then  dropping  back  into 
the  next  notch.  The  various  sections  show  the  cylinder  just  before  the 
rotary  movement  commences  and  just  after  it  has  taken  place,  the  lock- 
ing bolt  being  shown  in  place  in  one  view  and  withdrawn  in  another. 


Till-:    IXDKXIXG   MECHANISM  125 

Further  explanation  of  the  mechanism  is  unnecessary  as  the  drawings 
illustrate  the  scheme  fully.  It  may  be  stated,  however,  that  the  index 
notches  for  the  lock  bolt  are  formed  in  tool-steel  shoes,  secured  in  rect- 
ano;ular  pockets  in  the  peripliery  of  the  cylinder. 

The  machine  illustrated  has  a  capacity  for  1^-inch  round  stock,  1-inch 
hexagon,  and  f-inch  square  stock. 


CHAPTER   XIV 

The  Cleveland  Automatic  Machine  with  Magazine  Feed 

The  magazine  attachment  for  enabling  the  Cleveland  automatic 
turret  machine  to  handle  small  castings  and  forgings  requiring  opera- 
tions on  one  or  both  ends  is  represented   in  Fig.   Ill,  which   illustrates 


Fig.  111.  —  Cleveland  Automatic  Turret  Machine  with  Magazine  Attachment 

the  appliance  in  working  position.  The  attachment  is  made  in  two 
forms,  the  older  model  being  placed  on  the  rear  of  the  cross  slide  and  oper- 
ated by  a  cam  on  the  regular  cam  shaft  engaging  with  levers  at  the  rear 
of  the  magazine.  The  later  design  or  tilting  magazine,  as  illustrated,  is 
mounted  on  a  shaft  held  horizontally  by  two  upright  brackets  fastened  to 

126 


THE   CLEVELAXD   AUTOMATIC   MACHINE   WITH   MAGAZINE   FEED      127 


arms  on  the  bed  of  the  machine,  and  is  tilted  in  front  of  the  turret  when 
the  conveyor  or  transfer  device  is  in  position  to  take  a  piece  out  to  be 
chucked;  it  is  then  tilted  back  avoiding  interference  with  tools  in  the 
turret  or  on  the  cross  slide.  It  is  operated  in  the  same  manner  as  the 
older  model.  The  conveyor  is  held  in  one  of  the  tool  holes  of  the  tur- 
ret. It  grips  the  part  in  the  magazine  at  the  proper  moment  and  carries 
it  in  line  with  the  spindle,  where  the  work  is  chucked,  machined,  and 
ejected  to  make  way  for  the  next  piece  removed  from  tlio  magazine. 


li<i.  11. 


.Maciuniiisi  ;i  I'lsioii  in  a  (k'M'laiul  Maiia- 
zine  Machine 


Fig.  1 12  shows  a  method  of  handling,  in  the  magazine  of  a  large  Cleve- 
land machine,  a  piston  for  automobiles.  The  piston  is  about  5^  inches 
diameter  and  6  inches  long.  The  engraving  illustrates  plainly  the  turning 
tool  fastened  to  the  face  of  the  turret.  This  tool  takes  a  roughing  cut  on 
the  outside  of  the  piston  and,  as  the  turret  revolves,  it  brings  the  tool  on 
the  opposite  side  in  contact  and  takes  a  finishing  cut.  The  conveyor 
is  made  with  blades  fastened  to  a  holder  in  the  turret.  The  short  tool 
shown  above  it  is  for  boring  out  and  chamfering  the  end  of  the  piston, 
preparing  it  for  the  grinding  operation.  The  tools  on  the  cross  slide  in 
front  rough  out  the  ring  grooves  and  the  clearance  in  the  center,  and 
face  down  the  end;  the  tool  on  the  slide  at  the  rear  finishes  the  ring. 


CHAPTER  XV 

The  Alfred  Herbert  Magazine  Automatic  Screw  Machine 

In  Fig.  113  is  illustrated  an  automatic  magazine  screw  machine  built 
by  Alfred  Herbert,  Ltd.,  for  handling  castings.     The  castings  shown  are 


Fig.  ilo. 


Alfivd  llcrlicrl  Mufiaziiu'  Maeliiiu' 
128 


SPINDLE  AND  CHUCK 


129 


used  for  electric  cable  connections.  The  machine  is  illustrated  with  the 
magazine  full,  ready  for  work  and  with  a  finished  piece  in  the  chuck,  and 
upon  the  turret  slide  will  be  seen  several  sizes  and  types  of  castings  for 
which  the  machine  is  fitted  up. 


SPINDLE    .\ND    CHUCK 


Fig.   114  shows  the  spindle  and  chucking  mechanism,  and  Fig.   115 
the  construction  of  the  magazine.     The  chuck  is  of  the   three-jaw  type 


Fig.   114.  —  Spindle  and  Chuck 


and  operates  against  a  stiff  steel  spring  in  the  spindle,  thus  allowing  for 
variations  in  the  rough  castings.  The  jaws  are  provided  with  liners  to  suit 
different  sizes,  these  liners  being  readily  changed.     The  manner  in  which 


Fig.   115.  —  The  Magazine 


the  chuck  is  opened  and  closed  is  clearly  shown  in  the  drawing  and  needs 
no  explanation.  The  rod  at  the  center  of  the  spindle  ejects  the  work 
when  it  is  completed. 


130      ALFRED    HERBERT   MAGAZINE   AUTOMATIC   SCREW   MACHINE 

MAGAZINE    FOR    SHELLS 

The  manner  in  which  the  work  is  fed  from  the  magazine  into  the  chuck 
is  more  clearl}'  seen  in  Figs.  116,  117,  and  118.  In  this  case  the  machine 
is  shown  fitted  up  for  one-pounder  shells  for  quick-firing  guns.  Although 
the  work  is  of  a  somewhat  different  nature  from  that  in  the  machine  in 
Fig.  113,  the  magazines  are  practically  alike.  The  shells,  which  are  made 
from  a  high  grade  of  cast  steel,  have  been  bored  out  straight,  formed  out- 
side and  cut  off  in  a  previous  operation  in  another  machine,  and  the 
function  of  the  machine  here  shown  is  to  chamber  out  the  interior  of  the 
shell  and  thread  the  hole.  The  spindle  carries  a  draw-back  chuck,  and 
in  this  chuck  is  a  bushing  which  forms  a  stop  for  the  shells  and  also  admits 
the  end  of  the  ejector. 

THE    SHELL    FEED 

The  upper  trough  of  the  magazine  is  kept  filled  with  shells  which  are 
fed  forward  periodically  b}'  means  of  the  long  bar  carrying  the  small 
adjustable  pawls  shown  immediately  above  the  trough,  the  feed  bar  being 
moved  by  a  lever  operated  by  a  cam  on  the  drum  below.  From  the 
trough  the  shells  are  fed  one  at  a  time  into  a  rotating  carrier  attached 
to  a  rising  and  falling  slide.  In  Fig.  116  a  shell  has  just  been  fed  into 
the  carrier.  After  the  shell  already  being  operated  upon  has  been  com- 
pleted it  is  ejected.  The  carrier  then  descends  to  the  position  shown  by 
Fig.  117,  where  the  next  shell  is  just  about  to  enter  the  chuck.  It  is 
pushed  into  the  chuck  by  means  of  a  plunger  in  the  carrier,  this  plunger 
being  moved  by  a  spring  plunger  in  the  turret.  At  the  same  time  another 
small  plunger  is  pushed  in  by  an  adjustable  projection  on  the  turret  and 
releases  the  carrier,  which  turns  o^'er  under  the  action  of  a  flat  spring  like 
a  clock  spring,  and  assumes  the  position  shown  in  Fig.  118.  In  this  view 
the  shell  is  chucked  and  ready  for  machining. 

The  carrier  is  now  raised  to  its  original  position  in  Fig.  116,  and  on 
its  way  up  is  turned  over  to  its  proper  position  by  means  of  a  rack  which 
engages  with  a  gear  ring  on  the  carrier  hub. 

THE    CARRIER   MECHANISM 

The  carrier  mechanism  is  shown  in  Fig.  119,  in  which  A  is  the  carrier 
proper  and  B  the  gear  ring,  which  is  a  free  fit  upon  the  hub.  At  C  this 
hub  is  provided  with  a  series  of  ratchet  teeth  which  engage  with  a  pawl  D 
upon  the  gear  ring.  E  is  a  small  plunger  carrying  a  tooth  F  which  en- 
gages with  clutch  teeth  at  the  back  of  the  carrier  and  holds  it  in  the  position 
shown,  against  the  action  of  the  clock  spring  G.  It  will  l)e  seen  from 
this  drawing  that  when  the  carrier  descends,  the  gear  ring  will  rotate 
freely  upon  the  carrier  without  turning  it,  the  pawl  slipping  over  the 
ratchet  teeth.     When  the  carrier  rises,  however,  after  having  been  turned 


THE   CARRIER    MECHANISM 


131 


132      ALFRED  HERBERT  MAGAZINE  AUTOMATIC  SCREW   MACHINE 

over  by  the  clock  spring,  on  the  release  of  the  plunger  E,  the  rack  on  the 
magazine  rotating  the  gear  wheel  transfers  this  motion  through  the  pawl 
to  the  carrier  and  thus  rotates  it  back  into  its  original  position. 


Fig.  119.  —  Rotating  Carrier 


OPERATION    OF    THE    CARRIER 

The  lever  for  moving  the  vertical  slide  in  which  the  carrier  is  mounted, 
is  clamped  on  a  square  shaft  shown  at  the  back  of  the  attachment.  This 
shaft  is  rocked  by  a  short  lever  which  is  connected  by  an  adjustable  rod 
with  the  cam  lever  hung  below  in  the  frame  of  the  machine.  This  lower 
lever,  being  moved  by  a  cam,  has  a  fixed  stroke;  but  by  adjusting  the  nuts 
on  the  connecting  rod,  the  position  of  the  slide  —  when  the  cam  lever 
roll  is  on  the  highest  point  of  the  cam  —  may  be  varied  to  bring  the  carrier 
into  correct  alinement  with  the  work  on  the  magazine.  On  the  downward 
movement  the  slide  is  stopped,  with  the  work  in  line  with  the  chuck,  by 
means  of  an  adjustable  stop  collar  placed  on  one  of  the  vertical  rods. 
This  adjustment  at  top  and  bottom  is  very  important,  as  the  position 
of  the  carrier  must  vary  with  the  diameter  of  the  work.  In  addition  to 
the  vertical  adjustment,  the  magazine  has  an  adjustment  endwise  to  and 
from  the  chuck. 

ADVANTAGE    OF    THE    MAGAZINE 

This  type  of  magazine  has  been  used  by  the  firm  for  chucking  all 
kinds  of  pieces  where  the  length  is  greater  than  the  diameter,  one  of  its 
advantages  being  that  the  same  form  of  trough  can  be  used  for  a  great 
variety  of  work.  In  cases  where  the  pieces  will  not  lie  in  the  trough  in 
such  a  position  that  they  can  be  easily  chucked,  small  shoes  are  made 
to  carry  them.  These  shoes  hold  the  pieces  level  until  they  are  chucked 
and  then  drop  off  into  the  tray.  They  can  afterwards  be  collected  and 
used  over  again. 


CUTTING   THE   CHAMBER 


133 


THE    CHAMBERING    TOOLS 

In  forming  the  chanilDer  in  the  steel  shells  three  turret  tools  are  used, 
each  tool  being  adjusted  to  do  its  share  of  the  work.  The  construction 
of  the  tools  is  shown  in  Fig.  120.  The  body  A,  provided  with  a  shank 
fitting  the  turret  hole,  is  cut  out  dovetailed  at  the  bottom  to  receive  a 
slide  B.     On  this  slide  is  secured  a  former  C,  which  is  shaped  to  suit  the 


Fig.   120.  —  Tool  for  Forming  Chamljer  in  Shell 

chamber  in  the  shell.  A  long  spring  D  holds  the  slide  back  in  place  on 
the  body  A.  The  cross  shde  E,  fitted  to  the  top  of  .4,  carries  the  tool 
bar  F,  this  bar  being  provided  with  a  hole  for  admitting  oil  to  lubricate 
the  tool  and  wash  out  the  chips.  In  the  cross  slide  is  a  screw  G  carrying 
a  shoe  H,  which  is  held  against  the  former  C  by  means  of  the  spring  J. 
By  turning  the  screw  G  the  tool  can  be  adjusted  to  the  cut. 

CUTTING    THE    CHAMBER 

The  tool  is  run  in  to  the  bottom  of  the  hole  and  cuts  on  the  return. 
When  the  turret  moves  up,  carrying  the  tool  into  the  shell,  a  spring  plunger 
K,  fitted  in  a  holder  secured  to  the  front  end  of  the  turret-slide  block, 
engages  with  a  tooth  L  on  the  bottom  of  the  former  slide  B.     The  slide 


134       ALFRED  HERBERT  MAGAZINE  AUTOMATIC  SCREW   MACHINE 

is  thus  kept  from  moving  when  the  turret  is  drawn  back.  The  former 
being  held  in  position,  the  shoe  H,  as  it  shdes  along,  moves  the  cross  slide 
E,  and  the  cutting  tool  forms  the  chamber  in  the  shell. 

When  the  shoe  reaches  the  back  of  the  former  it  snaps  over  the  end, 
the  spring  returning  the  cross  slide  to  its  central  position,  so  that  the 
cutting  tool  —  as  it  is  withdrawn  by  the  turret  —  will  clear  in  the  smaller 
hole  in  the  outer  end  of  the  shell.  When  the  turret  rotates,  a  pin  M  in  a 
spring  plunger  N  in  the  back  of  the  body  A,  strikes  a  steel  plate  0  behind 
the  turret  and  forces  the  plunger  ahead.  This  plunger  is  milled  out  at 
P  and  in  the  notch  rests  a  pin  Q  carried  in  the  bottom  of  the  cross 
slide  E.  When  the  plunger  is  forced  ahead  by  the  plate  0  the  inclined 
surface  at  P  moves  the  pin  Q  and  slide  E.  The  shoe  H  thus  being  with- 
drawn from  behind  the  former  C,  the  slide  B  is  forced  back  by  the  spring 
D  into  its  original  position  in  the  holder. 

THE    TAP    HOLDER 

The  tap  for  the  hole  at  the  back  of  the  shell  is  carried  in  a  self-releas- 
ing holder  shown  in  place  in  Fig.  116.  The  teeth  on  this  holder  disengage 
when  the  tap  has  reached  the  required  depth.  When  the  spindle  reverses, 
a  spring  pin  in  the  holder  engages  with  a  ratchet  on  the  shank  of  the 
socket,  holding  it  stationary  while  the  tap  is  withdrawn.  The  holder 
is  carried  in  a  socket  provided  with  a  spring  which  gives  the  pressure 
necessary  for  starting  the  thread  when  the  tap  is  brought  up  to  the  work. 


CHAPTER   XVI 

The  Potter  &  Johxston  Automatic  Chucking  and  Turning  Machine 

The  "manufacturing  automatics"  made  by  Potter  &  Johnston, 
Pawtucket,  R.  I.,  are  adapted  for  handling  castings,  forgings,  and  bar 
stock  up  to  large  diameters;  all  operations  after  the  chucking  of  the  piece 
being   performed    automatically.     The    machine   sizes   are   5^  x  10   inch 

and  8+  x  16  inch;  and  both  are  built  with  trii^le-geared   and  direct  belt 


Fig.   121.  —  Potter  &  Johnston  Manufacturing  Automatic 

driven  heads  and  with  various  sizes  of  spindles  ranging  from  a  diameter 
of  3  inches  with  a  l^^^-inch  hole,  for  operating  on  small  work  at  high 
speeds,  to  7f  inches  diameter  with  G^-inch  hole  for  taking  bar  stock  up 
to  6  inches  and  machining  heavy  castings  and  forgings.  The  machine 
illustrated  in  Figs.  121  and  122  and  known  as  the  8^  x  16  inch  model 
has  a  spindle  diameter  of  of  inches,  the  hole  through  the  spindle  having 
a  diameter  of  4^  inches. 

THE    SPINDLE    DRIVE    AND    SPEEDS 

As  will  be  seen  upon  examining  the  rear  view  in  Fig.  122  the  machine 
is  driven  by  a  plain  pulley  mounted  on  the  back  shaft  which  is  geared  to 

135 


136    THE   POTTER   &   JOHNSTON   AUTOMATIC   CHUCKINfx   MACHINE 

the  spindle.  Two  rates  of  speed  are  obtained  through  the  gearing,  the 
spindle  revolving  always  in  one  direction;  right-  and  left-hand  tapping, 
however,  can  be  done  by  special  arrangement,  without  reversing.  The 
two  speed  changes  are  obtainable  automatically,  thus  making  it  prac- 
ticable to  run  at  a  suitable  speed  for  drilling  say  a  small  hole  and  turning 
the  hub  of  a  piece,  and  then  drop  to  a  reduced  speed  for  machining  the 
larger  periphery  of  the  work.  A  set  of  change  gears  for  the  spindle  drive 
are  provided  for  giving  the  correct  speeds  for  any  work  within  the 
capacity  of  the  machine,  the  speeds  of  course  being  determined  prior  to 
starting  operations  on  the  w^ork. 


Fig.   122.  ^Potter  &  Johnston  Mannfactuiin<i  Automatic  (Rear  View) 

The  speeds  are  controlled  by  adjustable  dogs  on  the  right-hand  side 
of  the  cam  disk  shown  directly  underneath  the  chuck.  The  dogs  actuate 
at  the  predetermined  moment  a  horizontal  rod  connected  to  the  vertical 
clutch  lever  at  the  left-hand  end  of  the  head  and  thus  cause  either  the  fast 
or  slow  speed  to  be  thrown  into  or  out  of  action.  The  vertical  crank 
handle  at  the  front  of  the  head  and  to  the  right  of  the  speed-clutch  lever 
connects  the  driving  pulley  at  the  back  of  its  shaft  or  releases  it,  thus 
forming  a  convenient  means  of  starting  and  stopping  the  machine  without 
interfering  with  the  countershaft. 


THE    FEED    MECHANISM 


Both  turret  and  cross  slides  are  operated  automatically  from  the 
main  cam  shaft  placed  longitudinally  of  the  machine.  This  shaft  is  driven 
from  the  spindle  by  a  belt  leading  over  the  pulleys  shown  at  the  end  of 
head  and  bed.     The  lower  pulley  operates  through  spur  gears  an  epi- 


BACK-FACING   BAR  137 

cyclic  train  connected  to  the  cam  shaft,  and  by  means  of  this  epicyclic 
gearing  and  suitable  clutches  the  cam  shaft  may  be  given  a  slow  speed 
for  the  cutting  travel  of  the  tools  and  a  rapid  velocity  for  quickly  with- 
drawing the  tools,  indexing  the  turret  and  bringing  it  forward  again  to 
cutting  position. 

The  speed  changes  of  the  cam  shaft  are  controlled  by  dogs  on  the 
opposite  side  of  the  disk  which  carries  the  spindle-controlling  dogs 
referred  to  above.  A  dog  carried  by  this  disk  also  stops  the  feed  when 
the  work  is  finished. 

Four  rates  of  feed  for  cutting  operations  are  provided  by  a  quick 
change  gear  in  the  base.  Having  determined  upon  the  proper  feed  for 
handling  a  job,  the  change-feed  gear  lever  is  dropped  into  the  notch 
to  correspond  with  the  feed  desired.  It  frequently  happens,  however, 
that  a  finer  or  coarser  feed  than  that  originally  provided  for  should  be 
used,  the  operator  then  simply  moving  the  change-feed  gear  lever  which 
projects  through  the  door  at  the  front  of  the  machine  either  to  the  right 
or  left,  and  dropping  it  into  one  of  the  notches  which  are  numbered 
"2-1-3-4."  When  the  handle  is  placed  in  the  notch  bearing  no  number, 
the  feed  is  thrown  out. 

THE    TURRET    AXD    CROSS    SLIDES 

The  turret  is  five-sided  and  the  slide  on  which  it  is  mounted  is  oper- 
ated by  the  large  cam  drum  on  the  main  shaft.  The  turret  is  clamped 
in  each  position  as  it  indexes  around  and  is  thus  held  rigidly  while  the 
tools  are  at  work. 

The  form  of  the  cam  is  plainly  seen  in  the  two  general  views.  The 
cams  in  the  regular  equipment  are  suited  to  all  ordinary  work  up  to 
9  inches  in  length  and  special  cams  can  be  used  for  pieces  of  unusual 
character. 

The  cross  slide  has  front  and  rear  tool  posts  and  the  tools  may  be 
arranged  to  work  at  the  same  time  the  turret  tools  are  cutting  or  inde- 
pendently of  these  tools.  The  slide  is  adjustable  longitudinally  on  the 
bed  and  the  cams  wdiich  operate  it  are  placed  at  the  right-hand  end  of 
the  cam  drum  for  the  turret  slide  where  they  are  readily  adjusted  from 
the  front  of  the  machine. 

Fig.  123  shows  the  cross-slide  cams,  the  oblique  rack  which  they  oper- 
ate and  the  gear  which  meshes  with  the  rack  and  turns  the  back  shaft 
which  is  in  turn  connected  by  a  similar  gear  with  a  rack  under  the  cross 
slide.  This  line  drawing  and  the  rear  view,  Fig.  122,  show  the  means  of 
operation  clearly. 

BACK-FACING    BAR 

The  automatic  back-facing  bar  through  the  spindle  is  an  important 
feature.     The  end  of  the  bar  is  provided  with  a  taper  hole  to  carry  drills, 


138     THE   POTTER   &   JOHNSTON   AUTOMATIC   CHUCKING   MACHINE 

cutters,  facing  tools,  either  singly  or  in  combination,  and  by  their  use 
a  large  variety  of  pieces,  such  as  gears,  pulleys,  etc.,  may  be  finished 
complete  at  one  holding,  the  back-facing  tools  finishing  the  inner  end 
of  the  hub  and  turning  it,  while  the  turret  and  cross-slide  tools  are  turn- 
ing the  periphery,  facing  down  both  edges  of  the  rim,  the  outer  hub,  and 
boring  the  hole.     By  this  arrangement  it  is  possible  to  have  as  many  as 


Fig.   123.  —  Cross-Slide  Cams  and  Connecting  ]\Iechani.sm 

eight  cutting  tools  in  simultaneous  operation,  thus  completing  the  work 
expeditiously.  Where  extreme  accuracy  is  required,  a  double  back- 
facing  bar  with  cutters  for  roughing  and  finishing  chips  may  be  applied. 
The  arrangement  of  the  back-facing  bar  and  the  method  of  operation 
will  be  understood  from  the  illustrations. 


MACHINE    WITH    LARGER    SPINDLE 

The  engraving,  Fig.  124,  is  presented  to  illustrate  the  8^  x  16-inch 
machine  as  constructed  with  7f-inch  spindle  adapted  for  receiving  bar 
stock  up  to  6  inches  diameter.  This  view  shows  in  addition  to  other 
interesting  details,  the  centering  chuck  at  the  rear  end  of  the  head  for 
gripping  and  supporting  the  stock. 

TOOL    EQUIPMENT 

The  general  character  of  the  tools  used  on  this  type  of  machine  is 
indicated  in  Figs.  125  and  126,  which  show  the  machine  set  up  for  turn- 
ing, boring  and  facing  operations.  The  combination  tools  and  their 
functions  will  be  understood  without  explanation.  Another  interesting 
job  is  represented  in  Fig.  127,  which  illustrates  the  method  of  machining 


TOOL    EQUIPMEXT 


139 


Fig.   124.  —  8^  X  16  inch  Potter  A:  Johnston  Manufac- 
turins:  Automatic 


gas  engine  pistons  and  is  also  self-explanatory.  A  few  specimens  of  the 
completed  work  produced  on  the  machines  are  shown  in  Fig.  128,  which 
suggests  the  range  of  diameters  falling  within  the  scope  of  the  machine. 


Fig.   !_'.">.        Turning,  Boring,  anel  Fatin^ 


140     THE   POTTER   &   JOHNSTON   AUTOMATIC  CHUCKING   MACHINE 


TOOL    RECORD 


Figs.  129  to  132  show  the  four  pages  of  a  convenient  tool  record  sheet 
issued  by  the  manufacturers  and  on  which  are  recorded  the  tool  and 
dog  settings,  change  gears,  etc.,  for  a  piece  after  the  work  has  been  set 


Fig.  126.  —  Turning  a  Spoked  Fly-wheel 

up.  At  any  time  afterward  the  settings  may  be  readily  duplicated  by 
simply  referring  to  the  sheet,  the  features  and  advantages  of  which  are 
well  brought  out  in  the  illustrations. 


Fig.   127.  —  Machining  a  Gas  Engine  Piston 


MACHINE    C.\PACITIES,    ETC. 

The  8^  X  16  inch  machine  illustrated  swings  20  inches  over  the  bed 
and  10  inches  over  the  cross  slide.  The  travel  of  the  cross  slide  each 
way  is  5^  inches.  The  5^  x  10  inch  machine  swings  17  inches  over  the  bed 
and  10  inches  over  the  cross  slide.  The  gear-driven  heads  of  the  type 
shown  are  operated  from  a  single-speed  countershaft  driven  by  a  pair  of 


MACHINE   CAPACITIES,   ETC. 


141 


tight  ami  loose  pulleys  and  carrying  a  plain  pulley  belted  to  the  machine. 
The  countershaft  for  the  machines  with  direct-belted  head  is  operated 
by  three-step  cone  pulleys.  When  the  machines  are  equipped  for  motor 
drive  the  motor  is  mounted  on  a  bracket  directly  behind  the  head. 


Fig.   128.  —  Some  of  the  Work  done  on  the  Potter  cV:  Johnston  Machine 


Either  size  of  machine  with  the  smaller  spindles  may  be  equipped 
with  a  lever  chuck  which  can  be  operated  to  admit  or  release  work  with- 
out stopping  the  spindle,  this  being  of  especial  advantage  when  machin- 
ing small  work  from  the  bar  or  handling  comparatively  light  castings 
and    forgings. 


142     THE    POTTER    tt    JOHNSTON    AUTOMATIC   CHUCKING   MACHINE 


THE  POTTER  &  JOHNSTON  AUTOMATIC  CHUCKING  MACHINE      143 


*  o  O  S  - 


5  i!il?1i^8=f •*!•:?  ^ 


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s: 


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i 


lis 


III 


III 


'2  -^ 


CHAPTER   XVII 


The  Gridley  Semi-Automatic  Pistox  Rixg  Machine 

This  machine  is  in  general  design  quite  similar  to  the  Gridley  auto- 
matic machine  for  bar  stock  described  in  Chapter  VII.  It  is  constructed 
especially  for  making  from  the  casting  piston  rings  ready  for  grinding 
on  the  edge.  The  operator  secures  the  casting  to  the  studs  in  the  face 
plate  and  the  machine  then  bores  the  inside,  turns  the  outside  eccentric, 
and   cuts  the  ring  off  from  the  casting  automatically.     Fig.    133  shows 


P^iG.   133.  —  Gridiey  Semi-Automatic  Piston  Ring  Machine 

the  machine  as  a  whole;  Fig.  134  illustrates  the  method  of  holding  the 
special  casting  to  the  face  plate  and  shows  the  means  of  operating  the 
tools;  Fig.  135  is  a  drawing  of  the  casting  from  which  the  piston  rings 
are  made. 

ECCENTRIC    TURNING    MECHANISM 

Fig.  136  is  a  construction  drawing  of  the  eccentric  turning  mechanism. 
In  this  engraving  A  represents  the  head  of  the  machine  carrying  the  spindle 

144 


ECCENTRIC  TURNING  MECHANISM 


145 


Fig.  134.  —  Boring,  Turning,  and  Cutting  Off  Piston  Rings 


N'otch  in  Castinsa 


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Thi5  Inside  Diameter 
must  Run  true  with 

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three     H  Holes    la 

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Flange   for   holding 

&^ 

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Casting  to  Face-plate. 

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Fig.  135.  —  Casting  from  wliich  Piston  Rings  are  Made 


Fig.  136.  —  Eccentric  Turning  Mechanism  for  Piston  Rings 


146     THE    GRIDLEY   SEMI-AUTOMATIC   PISTON   RING    MACHINE 

B  to  which  is  attached  the  face  phite  C.  This  face  pLate  carries  the  gear 
D  which  meshes  Avith  the  driving  gear  E,  to  which  is  attached  the  coupling 
F  pinned  to  the  shaft  G.  This  shaft  is  supported  in  the  slide  H  by  the 
two  bushings  /  and  /'.  It  carries  the  eccentric  J  and  drives  it  by  the  key 
K  which  is  free  to  move  endwise  in  the  keyway  in  the  shaft  G.  The 
eccentric  J  is  free  to  revolve  in  the  square  l)lock  L,  and  the  latter  is  free 
to  move  vertically  in  the  guideway  in  the  auxiliary  slide  M.  This 
arrangement  gives  the  slide  M  a  reciprocation  for  each  revolution  of  the 
spindle;  the  gears  D  and  E  being  of  even  diameter.  It  will  be  noticed 
that  the  construction  provides  an  oil  pocket  at  0,  which  keeps  the  parts 
thoroughly  lubricated.  The  gear  E  runs  free  on  the  bushing  .Y  held  in 
the  frame  of  the  machine  by  the  cap  Y.  The  same  bushing  .Y  acts  as  a 
bearing  for  the  back-gear  shaft  which  drives  the  spindle. 


CHAPTER    XWll 

The   Prentice   Multiple-.Spixdle   Auto:\iatic  Turret   Machixe 

The  multiple-spindle  automatic  built  by  the  Geo.  G.  Prentice  Co., 
New  Haven,  Conn.,  is  shown  in  the  accompanying  illustrations.  This 
machine  is  designed  for  performing  boring,  turning,  threading,  and  other 
operations  on  castings,   forgings,  and  similar  parts,  also  on  pieces  that 


Fig.   V.n.  —  Prentice  Multiplc-SpIndle  Automatic  Turret  Machine 

have  been  finished  on  one  end  in  a  bar-stock  machine.  It  is  especially 
adapted  to  the  handling  of  such  parts  as  air-brake-valve  bodies,  couplings 
and  nuts,  globe  valves,  grease  cups,  compression  hose  and  fuller  bibbs, 
gage-  and  ball-cock  bodies,  valve  stems,  etc.  The  machine  shown  has 
four  spindles,  these  being  arranged  in  the  manner  indicated  in  Figs.  137 
and  138.  Each  of  the  spindles  carries  a  tool  for  a  different  operation, 
and  the  work  is  automatically  indexed  and  fed  up  to  the  tools  by  a  cam 
drum,  which  will  be  seen  in  Fig.   137,  near  the  right-hand   end  of  the 

147 


148     PRENTICE   MULTIPLE   SPINDLE-AUTOMATIC   TURRET   MACHINE 

machine.  The  work  carrier,  or  turret,  consists  of  a  chuck  provided  with 
five  distinct  sections  or  sets  of  jaws,  each  pair  of  jaws  except  tlie  upper 
one  being  in  line  with  one  of  the  spindles;  the  upper  section  forms  the  point 
at  which  the  operator  feeds  the  work  to  the  chuck. 


Fig.   138.  —  Prentice  Multiple-Spinclle  Automatic  Turret  Machine 
THE    DRIVING    MECHANISM 

The  drive  for  the  four  spindles  and  cam  drum  will  be  understood 
from  the  general  views.  The  first  spindle  —  the  one  in  front  —  is  geared, 
as  shown,  to  a  shaft  driven  independently  from  the  counter,  while  the 
two  lower  spindles  are  geared  together  and  driven  by  the  large  pulley 
at  the  end  of  the  head.  The  threading  spindle  is  provided  with  friction 
reversing  pulleys  and  back-geared,  the  ratio  in  the  case  of  the  machine 
illustrated  (which  is  known  as  the  No.  23)  being  4  to  1,  while  the  lower 
spindles  are  geared  from  their  driver  in  a  2.7  to  1  ratio,  and  the  front 
spindle  in  a  ratio  of  2  to  1.  The  cam  shaft  which  feeds  the  work  carrier 
up  to  the  tools  is  driven  from  either  the  third  or  fourth  spindle  by  change 
gearing  extending  to  a  shaft  at  the  rear  of  the  bed,  this  shaft  being  con- 
nected with  the  cam  shaft  —  which  extends  the  full  length  of  the 
machine  —  by  bevel  and  worm  gearing. 

THE    FEED 

The  feed  drum  is  adapted  to  receive  a  cam  strip  fixed  at  the  required 
angle,  this  being  determined  by  the  length  of  the  longest  cut  required 
on  the  piece  of  work.  An  adjustable  ring  on  the  threaded  end  of  the 
chuck  shaft,  or  turret  bar,  forms  a  positive  stop  for  each  forward  move- 
ment of  the  work  to  the  tools.  This  stop  collar  will  be  noticed  just  to 
the  rear  of  the  indexing  mechanism  which  brings  the  work  into  alinement 
with  one   spindle  after  another  until  completed.     The   feed  clutch  may 


INDEXING   FACE   PLATE 


149 


be  thro\vn  out  of  gear  and  the  feed  instantly  stopped  by  shifting  the 
lever  shown  near  the  left-hand  end  of  the  machine.  The  chuck  may  be 
fed  up  by  hand,  when  adjusting  tools  for  new  work,  by  turning  to  the 
left  the  worm  shaft  at  the  end  of  the  bed. 


OPERATION    OF   THE    CHUCK 

The  construction  of  the  chuck  is  shown  in  Fig. 
forms  a  two-jaw  chuck  opened  and  closed  b}^  a  right- 
and  special  false  jaws  are,  of  course,  fitted  to  hold 
As  already  stated,  the  work  is  placed  in  the  uppermost 
and  the  first  indexing  movement  then  brings  it  int 
in  the  first  spindle,  where  the  first  operation  is  perfor 
time  a  second  piece  of  work  has  l^een  placed  in  the 
the  chuck,  which  is  then  in  the  upper  position,  and 


139.  Each  section 
and  left-hand  screw, 
any  shape  of  piece, 
section  of  the  chuck, 
0  line  with  the  tool 
med.  In  the  mean- 
following  section  of 
when  the  first  piece 


Fig.  139  Fig.  140 

Chuck  and  Face  Plate  for  Prentice  Turret  Machine 

is  brought  into  line  with  the  second  tool,  the  first  tool  is  operating  on  the 
second  piece;  thus  each  indexing  movement  presents  each  piece  of  work 
to  a  different  tool  and  four  operations  may  be  carried  on  simultaneously; 
the  operator  simply  takes  out  the  finished  parts  and  puts  in  the  rough 
work  without  stopping  the  machine,  and  ordinarily  can  attend  to  two 
or  more  machines.  While  the  tools  are  cutting  the  chuck  is  supported 
and  relieved  of  strain  by  a  bracket  which  slides  under  the  ledge  of  the 
chuck  at  the  front  of  the  machine.  This  bracket  is  visible  in  Fig.  137, 
and,  as  there  shown,  is  attached  to  a  lever  which  automatically  draws 
it  back  out  of  the  way  of  the  chuck  before  the  latter  indexes,  and  then 
moves  it  to  supporting  position  again  before  the  tools  start  cutting.  A 
taper  bushing  in  the  chuck  body  forms  a  means  of  compensating  for  wear 
between  chuck  and  turret  bar. 


INDEXING    FACE    PLATE 

For  holding  work  that  has  been  finished  on  one  end  and  requires  a 
second  operation,  an  indexing  face  plate  is  used  in  place  of  the  chuck. 


150     PRENTICE   MULTIPLE-SPINDLE   AUTOMATIC   TURRET   MACHINE 

This  face  plate,  as  shown  in  Fig.  140,  has  five  drawback  studs  or  work 
arbors,  which  are  threaded  to  receive  work  having  internal  threads,  or 
provided  with  threaded  collets  for  externally  threaded  work.  After  a 
piece  of  work  has  been  screwed  on  a  few  turns  by  hand,  a  half  turn  of 
an  eccentric  stud  draws  it  back  tight  against  a  hardened  collar. 

The  spindles  of  this  machine  are  ground  and  run  in  bronze  bearings, 
the  front  bearings  being  taper,  and  all  but  the  threading  spindle  have 
tool  holders  forged  solid  on  the  spindle.  The  frictions  on  the  threading 
spindle  are  of  an  expanding  ring  type  and  controlled  l)y  a  lever  contact- 
ing with  a  tripping  disk  on  the  cam  shaft.  When  an  automatic  opening 
die  or  collapsing  tap  is  used,  the  threading  mechanism  is  locked  in  the 
forward  position,  and  the  reversing  belt  removed. 


TOOL    EQUIPMENT 

Fig.  141  illustrates  some  of  the  tools  adapted  to  this  machine.     The 
one  in  the  upper  left-hand  corner  is  for  cutting  external   and  internal 


Fiu.  141. 


Prentice  Turret  Machine  Tools 


annular  grooves,  and  consists  of  a  shank  and  head  with  a  cross  slide  and 
cutter  moved  at  right  angles  by  two  wedges.  For  internal  grooves  the 
tool  is  carried  at  the  center  of  the  slide.  A  spring-actuated  rod  returns 
the  slide  as  soon  as  the  pressure    on  the  work  is  removed.      The  tool  at 


ROTARY   CUT-OFF  151 

the  right  is  a  hollow  mill  which  automatically  opens  upon  the  completion 
of  the  cut.  The  three  tools  in  the  second  row  are  tap  and  die  holders, 
the  middle  one  being  a  combination  floating  affair  for  cutting  external 
and  internal  threads  at  the  same  time.  The  tap  holder  proper  slides 
on  two  studs  in  the  threading  spindle,  and  the  die  holder  on  two  studs 
in  the  tap  holder,  thus  allowing  a  tap  and  die  of  different  pitch  to  be 
used  together.  Both  types  of  tap  and  die  holders  shown  are  arranged 
to  be  led  on  the  work  by  feed  mechanism.  An  automatic  opening  die 
is  shown  in  the  lower  left-hand  corner,  and  at  the  right  are  a  j)air  of 
adjustable  roughing  and  finishing  turning  tools.  Among  other  tools 
used  are  boring  and  turning  tools,  counterbores,  etc.,  made  of  flat  bar 
stock  dressed  on  the  grinder  and  inserted  in  holders. 

UNDERCUTTING    TOOLS 

Some  details  of  the  tools  for  cutting  external  and  internal  grooves  of 
any  desired  form  are  presented  in  Figs.  142  to  149  inclusive.  The  tool, 
Fig.  142,  is  placed  in  one  of  the  spindles  of  the  machine  and  operated 
by  an  angular  wedge  and  cross-slide  mechanism,  the  wedges  being  made 
with  the  proper  angle  to  give  fast  or  slow  cross  motion  to  the  cutter 
head.  For  external  cuts,  a  ball-bearing  pilot  receives  the  thrust  of  the 
piece  of  work  as  the  chuck  is  fed  up  to  the  tools,  and  this  pressure  forces 
the  cutter  head  back  on  the  wedges  and  draws  the  cutter  down  into  the 
work.  When  the  advance  of  the  work  ceases,  and  the  chuck  starts  to 
back  off,  the  spring  in  the  hollow  spindle  forces  the  cutter  head  out  on 
the  wedges  and  the  tool  is  drawn  out  of  the  work.  For  cutting  internal 
grooves,  the  cutter  is  placed  on  the  opposite  side  of  the  head  from  where 
placed  for  external  work,  and  the  same  taper  wedges  are  used  for  both 
forms  of  cutting. 

INTERNAL    OPERATION 

Fig.  143  shows  the  shape  of  the  wedges.  Fig.  144  the  ball-bearing  pilot. 
In  Fig.  145,  neck  a  is  an  external  cut  made  with  this  tool.  For  internal 
cutting  a  circular  or  single-point  tool  is  mounted  on  a  special  head  used 
in  place  of  the  cutter  head  shown  in  Fig.  142.  Fig.  146  is  the  cutter  used 
for  the  inside  groove  h  in  Fig.  145.  Fig.  147  is  the  cutter  used  for  simul- 
taneously forming  the  two  inside  grooves  c  d  in  the  work.  Fig.  148.  On 
this  work  the  cross  motion  of  the  cutter  head  does  not  begin  until  the 
cutter  has  entered  the  work  and  the  face  of  the  work  comes  in  contact 
with  the  steel-thrust  washer  mounted  on  the  cutter  head. 

ROTARY    CUT-OFF 

There  are  certain  classes  of  work,  such  as  valve,  gage,  and  compression- 
bibb  spindles,  which  are  cast  with  a  chucking  lug,  from  which  the  finished 
piece  is  severed  after  all  the  operations  are  performed.     For  this  work 


152     PRENTICE  MULTIPLE-SPINDLE  AUTOMATIC   TURRET   MACHINE 


--3^ 


ITL. 


vf/////y////// 


■^yyy^>->y^\  ' 


FIG. 142 


Undercutting  Tools  for  Turret  Machine 


COUNTERSHAFT,    MACHINE   SIZES,    ETC. 


153 


a  rotary  cut-off  tool  is  mounted  in  place  of  one  of  the  regular  spindles  of 
the  machine.  As  the  tool  must  traverse  a  considerable  length  over  the 
finished  surface  of  the  work  to  bring  the  cutting-off  tool  to  the  point  of 
operation,  the  cutter  head  is  fed  out  by  means  of  the  rear  lever  and  cam 
as  shown  in  Fig.  149.  The  advance  of  the  chuck  brings  the  work  in  con- 
tact with  the  ball-bearing  pilot  in  the  cutter  head,  and  at  the  same  time 
the  forward  lever  and  cam  feed  the  cutter  into  the  work,  the  feed  being 
accelerated  by  means  of  the  angle  of  the  cam  as  the  tool  enters  the  work. 
When  the  operation  is  completed  a  return  cam  on  the  forward  drum  shifts 
the  lever  and  withdraws  the  cutter  from  the  work,  and  a  similar  cam 
shifts  the  rear  lever  and  the  tool  is  drawn  back  ready  for  the  next  opera- 
tion. 

COUNTERSHAFT,    MACHINE    SIZES,    ETC. 

The  arrangement  of  the  countershaft  and  driving  belts  is  represented 
in  Fig.  150. 

The  machine  illustrated  will  turn  a  length  of  5  inches  and  swing  5 


Fig.   1.50.  —  Countershaft  and  Drive  for  Prentice  Automatic  Turret  Machine 


inches  outside  of  the  chuck  jaws.  The  false  jaws  open  3j  inches.  The 
threading  spindle  receives  shanks  Ij^  inches  diameter  by  4^  inches 
long,  and  the  other  spindles  have  H  x  3-inch  holes.  The  threading 
capacity  is  up  to  f-inch  pipe  or  H  inches  straight.  There  are  three  other 
sizes,  the  largest  swinging  7  inches  outside  of  chuck  jaws,  turning  a  length 


154        PRENTICE  MULTIPLE-SPINDLE  AUTOMATIC  TURRET  MACHINE 

of  7  inches,  and  having  a  threading  capacity  for  pipe  up  to  2  inches  and 
straight  work  up  to  4  inches  diameter. 

DOUBLE-HEAD    MULTIPLE-SPINDLE    TURRET    MACHINE 

As  will  be  seen  by  referring  to  Fig.  151  this  machine  is  built  on  very 
similar  lines  to  the  single-end  machine  by  the  same  company,  but  is  double- 
ended  and,  therefore,  performs  boring,  facing,  drilling,  turning,  threading, 
and  other  operations  on  both  ends  of  a  piece  at  one  setting  in  the  chuck. 
The  standard  machine  has  three  spindles  in  each  end,  between  which  is 


Fig.   loL  —  Prentice  Six-Spindle  Double-Head  Automatic  Turret  Machine 

a  chuck  having  four  sections  or  sets  of  chuck  jaws.  The  spindles,  carry- 
ing the  tools,  are  in  line  with  the  different  sections  of  the  chuck,  except 
the  upper  section,  where  the  operator  removes  finished  work  and  inserts 
an  unfinished  piece  while  the  machine  operates  constantly  on  a  piece  of 
w^ork  in  each  of  the  other  sections  of  the  chuck. 


SPINDLE    OPERATION 

The  spindles  revolve  and  are  fed  up  to  the  work  by  means  of  yoke 
and  lever  connections  with  cams  on  drums  inside  of  the  bed,  the  cam 
shaft  extending  the  entire  length  of  the  machine.  The  forward-feed 
cams  are  set  at  the  proper  angle  to  give  the  required  advance  or  cutting 
feed  to  the  tools  on  the  work,  and  the  reverse  cams  draw  the  tools  back 
from  the  w^ork  when  the  operations  are  completed.  While  the  tools  are 
backing  off,  the  chuck  is  automatically  indexing  so  that  each  piece  of 
work  is  brought  in  line  with  the  spindles  which  perform  the  succeeding 
operations. 

The  movements  of  the  machine  are  timed  so  that  the  indexing  occurs 


GENERAL   DATA  I55 

as  soon  as  the  longest  single  operation  on  any  piece  of  work  is  completed. 
All  the  shorter  operations  are  completed  within  this  time,  hence  the 
time  of  finishing  a  piece  of  work  on  both  ends  is  the  time  necessary  for 
the  longest  single  operation  plus  a  few  seconds  taken  in  the  indexing  of 
the  chuck  and  the  advancing  of  the  tools. 

THREADING   MECHANISM 

As  the  chuck  indexes  toward  the  front  of  the  machine,  the  first  or 
roughing  spindles  are  at  the  front,  and  the  finishing  and  threading  spindles 
follow.  The  threading  mechanism  consists  of  a  sliding  tap  or  die  holder 
with  a  fork  lever  connecting  with  a  cam  to  start  the  lead  of  the  thread. 
The  driving  mechanism  consists  of  forward  and  reverse  friction  pulleys 
with  expanding  rings.  The  tap  is  driven  the  required  number  of  turns 
into  the  work,  then  the  reverse  is  automatically  engaged  and  the  tap  with- 
drawn. 

The  proper  cutting  feed  for  different  kinds  of  metal  is  obtained  by 
change  gears,  a  worm  and  worm  gear  connecting  with  the  main  feed 
shaft  on  which  all  cam  drums  are  placed.  The  spindles  are  back-geared 
and  have  ample  driving  power  for  work  within  the  rated  capacit}^  of  the 
machine. 

GENERAL    DATA 

Three  sizes  of  the  six-spindle  machines  are  built:  One  for  light  work, 
one  with  capacity  for  f-inch  pipe  size  threads  and  smaller,  and  one  for 
2-inch  down  to  f-inch  pipe  threads.  The  same  design  of  machine  is  also 
built  with  four  spindles  in  each  head  and  a  five-section  chuck,  the  three 
sizes  of  this  design  corresponding  in  threading  capacity  with  the  three 
six-spindle  machines.  The  eight-spindle  type  is  adapted  especially  to 
handling  bicycle  hubs  and  gas  and  electric  fixture  work.  All  these  ma- 
chines have  the  same  chuck-steadying  bracket  as  the  single-head  machine 
illustrated. 


SECTIOX   II 

SCREW   MACHINE   TOOLS 
METHODS    OF    MAKING    AND    USING    THEM 


CHAPTER   XIX 
Points  In  Setting  up  and  Operating  Automatic  Screw  Machines 

In  the  following  pages  a  few  general  suggestions  are  given  which  may 
be  of  interest  to  operators  before  considering  in  detail  the  different  types 
of  tools,  determination  of  speeds,  feeds,  etc.,  treated  fully  in  Chapters  XX 
to  XXVII. 

It  should  be  borne  in  mind  that  the  automatic  screw  machine  neces- 
sarily has  more  complicated  mechanism  than  a  hand-operated  machine, 
as  many  movements  must  be  performed  automatically,  which  in  the  hand 
type  of  machines  are  accomplished  by  the  operator.  The  automatic 
machines  must,  therefore,  have  the  more  careful  attention  in  setting  up 
for  turning  out  work.  When,  however,  the  machines  are  properly  adjusted, 
very  little  attention  over  that  recjuired  on  a  hand  machine  is  needed, 
although  the  use  of  dull  tools  must  be  particularly  guarded  against.  The 
machines  must  be  carefully  erected  and  leveled  up  so  as  to  avoid  poor 
alinement  between  head  spindle  and  turret,  etc. 

operator's  duties 

Ordinarily  a  workman  will  readily  attend  to  six  machines  and  on  very 
simple  straightforward  work  may  economically  look  out  for  more.  He 
should  become  thoroughly  familiar  with  the  machine  operations  and 
adjustments  before  putting  in  tools  or  starting  up,  and  it  is  generally  well 
first  to  operate  the  machine  by  hand  before  putting  on  power. 

Assuming  that  a  new  piece  of  work  is  to  be  produced  on  an  automatic 
screw  machine,  it  is  well  to  consider  first  the  various  ways  in  which  the 
work  may  be  machined,  and  to  give  due  consideration  to  the  tool  equip- 
ment available  and  to  the  quantity  of  pieces  to  be  made,  and  then  decide 
upon  a  satisfactory  method. 

tools  and  collets 

The  making  of  special  tools  and  the  changing  of  the  camming  of  the 
machine  (if  any)  must  then  be  attended  to.  All  tools  and  holders  must 
be  made  accurately  to  give  correct  results,  and  in  addition  it  is  always 
advisable  to  check  the  first  few  pieces  produced,  by  gages  or  otherwise, 
to  see  that  the  pieces  are  of  the  correct  dimensions.  The  collet  should 
grasp  the  rod  the  entire  length  of  the  bearing  surface,  and  have  a  tendency 

1.59 


160       SETTING    UP   AND    OPERATING   AUTOMATIC   SCREW    MACHINES 

to  bite  harder  on  the  front  end  than  at  the  rear.  This  affords  rigidity 
to  the  work  when  a  cross-forming  operation  is  being  performed.  The 
front  end  of  the  collet  should  likewise  have  a  good  bearing  in  its  seat. 
The  collet  when  closed  must  firmly  grip  the  rod  so  as  to  prevent  any 
slipping  under  the  action  of  the  cutting  tools. 

HANDLING    MATERIAL 

The  feeding  chuck  must  have  sufficient  grip  to  feed  the  rod  accurately 
without  undue  marring  of  the  material  upon  its  return  stroke.  It  is  gen- 
erally considered  well  to  straighten  the  bars  of  stock  if  they  are  bent,  and 
also  to  gage  them  for  diameter  and  to  stack  them  into  separate  bundles 
if  there  is  an  appreciable  variation  which  would  cause  difficulty  when 
machining,  and  afterwards  to  make  adjustment  of  the  collets,  etc.,  to 
suit  the  various  sizes  as  worked  up. 

Where  different  ciualities  of  steel  are  being  used,  extreme  care  must 
be  taken  to  prevent  mixing  in  a  hard  tool  steel  bar  with  the  soft  steel 
stock  from  which  the  work  is  supposed  to  be  made;  as  the  speed  of  the 
spindle  and  the  feed  may  be  such  as  to  ruin  expensive  tools. 

TOOL    AND    OTHER    ADJUSTMENTS 

It  is,  of  course,  obvious  that  the  lubricating  pump  should  be  known 
to  be  properly  working  and  all  cutting  tools  properly  set  with  regard  to 
the  work  and  their  cutting  edges  properly  ground  in  order  to  get  good 
results. 

The  head  spindle  bearings  must  be  adjusted  so  as  to  permit  running 
of  the  spindle  at  satisfactory  speed  without  unreasonable  freedom  —  else 
trouble  will  arise  from  this  source.  The  cross  slide,  turret  and  turret- 
slide  bearings  uTust  also  be  carefully  adjusted  and  kept  in  good  condition. 

The  selection  of  the  proper  spindle  speeds  for  various  jobs,  as  well 
as  the  determining  of  satisfactory  feeds  should  be  considered  carefully. 
In  the  next  chapter  are  tables  which  should  be  helpful  in  this  connection. 

PRODUCTION 

The  rate  of  production  is  dependent  not  only  on  the  rate  of  feed  and 
spindle  speed,  but  also  on  the  tool  equipment.  The  production  of  threaded 
work  especially  is  facilitated  by  employing  tools  so  designed  as  to  take 
advantage  of  two  speeds  and  to  cut  when  the  spindle  is  reversed. 

The  camming  should  be  such  as  to  permit  the  performing  of  several 
operations  simultaneously,  such  as  drilling  from  the  turret  and  forming 
from  the  cross  slide. 

MANIPULATION    OF    TOOLS 

When  changing  the  tool  equipment  from  one  piece  to  another  the  seat 
in  the  head  spindle  for  the  collet  must  be  thoroughly  cleaned  as  well  as 


BELTS,    OILING,   ETC. 


161 


the  collet,  so  as  to  avoid  eccentricity  in  the  operation  of  the  rod  due  to 
foreign  matter,  when  the  stock  is  grasped  by  the  collet. 

It  is  well  before  dismantling  tools  to  make  a  model  on  the  automatic 
screw  machine  for  convenience  in  setting  up  in  the  future.  This  model 
should  be  complete  in  all  respects,  but  should  not  be  fully  cut  off  to  its 
usual  length,  but  should  be  left  intact,  with  sufficient  length  of  the  bar  to 


tOiiP  [ 


Fig.  152. 


"Setting  L'p"  Models  for  the 
Screw  Machine 


permit  grasping  by  the  collet  allowing  the  model  to  be  the  proper  working 
distance  from  the  end  of  the  spindle.  The  illustration  in  Fig.  152  shows 
two  models  with  the  piece  of  stock  by  which  they  are  held  when  setting 
up  for  the  production  of  similar  work. 

BELTS,    OILING,    ETC. 

It  is  recommended  that  belts  without  rivets  be  used  for  the  spindle 
drive  as  they  run  smoothh'  at  high  speed.  Laced  wire  also  makes  a 
smoother  running  belt  than  where  leather  lacing  or  hooks  are  used  for 
coupling  the  ends  together.  On  machines  where  the  belts  are  shifted 
to  change  a  spindle  speed  or  the  direction  of  rotation,  double  belts  will 
be  found  superior  to  single  belts  as  the  former  being  of  stiffer  cross  section 
may  be  more  quickl}"  moved  and  the  results  desired  more  quickly  obtained. 

The  workmen  in  charge  of  machines  should  be  instructed  to  lubricate 
all  bearings  frequently  with  good  machinery  oil  and  should  be  thoroughly 
familiar  with  the  location  of  each  hole  and  its  function.  Too  much  atten- 
tion cannot  be  given  to  this  if  satisfactory  continuous  service  is  to  be 
expected  from  an  automatic  screw  machine. 

The  chapters  that  follow  in  this  section  describe  in  detail  various 
classes  of  tools  for  screw  machines  and  illustrate  methods  of  making  and 
using  them.  It  is  hoped  that  the  information  contained  therein,  with 
the  chapters  on  camming  and  illustrations  of  tools  in  Section  1,  may  be 
of  special  interest  and  service  to  toolmakers,  draftsmen  and  operators. 


CHAPTER   XX 

Speeds  and  Feeds  for  Screw  Machine  Work 

The  ordinary  class  of  screw  machine  tools,  suitable  speeds  and  feeds 
for  which  have  to  be  determined  when  camming  automatics,  includes 
the  various  turning  tools  such  as  box  tools  (adjustable  and  non-adjustable), 
hollow  mills,  drills,  reamers,  counterbores,  taps  and  dies,  forming  and 
cutting-off  tools.  The  accompanying  tables  of  speed  and  feeds  for  differ- 
ent types  of  tools  used  on  materials  commonly  worked  in  the  automatic 
have  been  compiled  from  data  accumulated  and  thoroughly  tested  during 
extended  experience  in  this  class  of  work  and  have  proved  of  value  in 
the  screw  machine  department,  not  only  in  connection  with  the  handling 
of  automatics,  but  also,  to  a  considerable  extent,  on  hand  machines, 
although,  naturally,  the  matter  of  feeds  on  the  latter  class  of  apparatus 
is  largely  regulated  by  the  personal  equation;  the  question  of  spindle 
speeds,  however,  is  quite  as  important  and  as  readily  settled  for  hand 
machines  as  for  automatics. 

It  is  of  course,  impossible,  where  a  series  of  tools  is  used  on  an  auto- 
matic machine  providing  say  two  rates  of  speed  for  the  spindle  for  any 
given  job,  to  select  speeds  theoretically  correct  for  each  and  every  tool 
carried  by  the  turret  and  cross  slide.  A  compromise  is  necessary  and 
therefore  speeds  are  selected  which  will  fall  within  the  range  suitable 
for  the  different  tools;  in  determining  these  surface  speeds  and  the  rates 
at  which  to  drive  the  spindle  to  approximate  closely  the  desired  surface 
velocities,  the  tables  should  be  found  of  service. 

speeds  and  feeds  for  turning 

Tables  15  and  16  cover  turning  speeds  and  feeds  for  bright-drawn 
stock  (screw  stock)  and  brass,  with  various  depths  of  chip  (that  is,  stock 
removed  on  a  side)  from  3V  inch  up  to  f  inch.  These  feeds  and  speeds 
and  depths  of  cut  are  figured  more  especially  for  such  tools  as  roughing 
boxes  where  the  cut,  though  frequently  heavy,  is  taken  by  a  single  cutting 
edge,  the  work  being  well  supported  behind  the  cutter  during  the  opera- 
tion.  Table  17  covers  the  same  range  of  steel  work  as  Table  15,  but  is 
laid  out  for  hollow-mill  operations;  it  will  be  noticed  that,  the  cut  being 
divided  with  this  tool  among  three  or  more  cutting  edges,  coarser  rates 
of  feed  are  provided  for  than  with  the  box  tool.     With  both  classes  of 

162 


SPEEDS  AND  FEEDS   FOR  TURNING 


163 


CUTTING  SPEEDS  AND  FEEDS  FOR  SCREW  STOCK. 

3<o  Inch  Chip 

Vfg  Inch  Chip 

\   Inch  Chip 

Dia. 

of 

Stock 

Feet 
Surface 
Speed 

Rev. 
per 
Min. 

Feed 
per 
Rev. 

Dia. 
of 

Stock 

Feet 

Surface 

Speed 

Rev. 
per 
Min. 

Feed 
per 
Rev. 

Dia. 

of 

Stock 

Feet 
Surface 
Speed 

Elev. 
per 
Min. 

Feed 
per 
Rev. 

J» 

80 

2445 

.002 

34 

60 

913 

.0035 

% 

55 

560 

.004 

J'i, 

70 

1426 

.003 

?a 

6) 

611 

.004 

H 

55 

420 

.005 

\ 

70 

1069 

.004 

yi 

GO 

458 

.005 

% 

55 

280 

.006 

% 

70 

713 

.005 

X 

55 

380 

.006 

1 

50 

191 

.007 

ii 

60 

458 

.006 

1 

55 

210 

.007 

154 

50 

152 

.007 

X 

60 

305 

.007 

134 

55 

168        .007 

13^ 

45 

114 

.007 

1 

60 

229 

.008 

l^ 

50 

127 

.008 

1?4 

45 

98 

.007 

IH 

60 

183 

.008 

IX 

50 

109 

.008 

2 

40 

76 

.008 

IH 

50 

127 

.009 

2 

45 

86 

.009 

234 

40 

68 

.008 

va 

50 

109 

.010 

2M 

45 

76 

.009 

Za 

40 

61 

.008 

2 

50 

95 

.010 

•2^ 

45 

68 

.009 

3 

40 

51 

.008 

234 

50 

85 

.010 

3 

45 

57 

.009 

334' 

40 

44 

.008 

Jii  Inch  Chip 

Ji  Inch  Chip 

?i  Inch  Chip 

Dia. 
of 

Stock 

Feet 
Surface 
Speed 

Rev. 
per 
Min. 

Feed 
per 
Rev. 

Dia. 

of 

Stock 

Feet 

Surface 

Speed 

Rev. 
per 
Min. 

Feed 
per 
Rev. 

Dia. 

of 
Stock 

Feet 
Surface 
Speed 

Rev. 
per 
Min. 

Feed 
per 
Rev. 

3^ 

50 

382 

.004 

5i 

50 

254 

.004 

134 

45 

137 

.005 

?^' 

50 

251 

.005 

1 

50 

191 

.005 

l^ 

45 

114 

.005 

1 

50 

191 

.005 

134 

45 

137 

.005 

IX 

45 

98 

.005 

134 

45 

137 

.006 

l>i 

45 

114 

.006 

2 

40 

76 

.006 

l>i 

45 

114 

.006 

154 

45 

98 

.006 

2^4. 

40 

68 

.006 

154 

45 

98 

.006 

2 

40 

76 

.OOo 

2M 

40 

61 

.007 

2 

40 

76 

.007 

234 

40 

68 

.007 

3 

40 

51 

.007 

2!4 

40 

68 

.007 

2>i 

40 

61 

.007 

3H 

40 

44 

.oor 

2>i 

40 

61 

.007 

3 

40 

51 

.007 

4 

40 

38 

.008 

3 

40 

51     j     .007 

33^ 

40 

44 

.007 

m 

40 

34 

.008 

Table  15.  —  Speeds  and  Feeds  for  Screw  Machine  Work 


164 


SPEEDS  AND   FEEDS   FOR   SCREW  MACHINE   ^VORK 


CUTTING  SPEEDS  AND  FEEDS  FOR  BRASS 

y,2  Insh   Chip 

X^  Inch  Chip 

'a   Inch  Chip 

Dia. 

of 

Stock 

Feet 

Surface 

Speed 

Kev. 
per 
Min. 

Feed 
per 
Kev. 

of 
Stock 

Feet 
Surface 
Speed 

Rev, 
per 
Min. 

Feed 
per 
Rev. 

Dia. 
of 

Stock 

Feet 
Surface 
Speed 

Rev. 
per 
Min. 

Feed 

per 

Rev. 

Vs 

180 

5500 

.003 

U 

180 

2748 

.004 

fi 

165 

1680 

.004 

Ke 

180 

3668 

.004 

h 

180 

1833 

.005 

X 

165 

1260 

.006 

K 

180 

2748 

.005 

H 

180 

1374 

.0065 

?^ 

165 

840 

.007 

/» 

180 

1833 

.006 

^■i. 

165 

840 

.0075 

1 

150 

573 

.008 

y^ 

180 

1374 

.008 

1 

165 

630 

.0085 

134 

150 

456 

.009 

K 

180 

915 

.010 

IX 

165 

504 

.010 

IX 

135 

342 

.010 

1 

180 

687 

.011 

IX 

150 

381 

.012 

154 

135 

294 

.010 

Ik. 

180 

549 

.012 

15.1 

150 

327 

.012 

2 

120 

228 

.011 

IX 

150 

254 

.014 

2 

135 

258 

.014 

234 

120 

204 

.011 

m 

150 

218 

.014 

23-4 

135 

228 

.014 

2k 

120 

183 

.012 

2 

150 

190 

.015 

2)4 

135 

204 

.014 

8 

120 

153 

.012 

2« 

150 

170 

.015 

3 

135 

171 

.014 

3X 

Jie  Inch  Chip 

34   Inch  Chip 

?3   Inch  Chip 

Dia. 

of 

Stock 

Feet 
Surface 
Speed 

Rev. 
per 
Min. 

Feed 
per 
Rev. 

Dia. 

of 

Stock 

Feet 
Surface 
Speed 

Rev. 
per 
Min. 

Feed 
per 
Rev. 

Dia. 

of 
Stock 

Feet 
Surface 
Speed 

Rev. 
per 
Min. 

Feed 
per 
Rev. 

}i 

150 

1146 

.005 

?i 

150 

762 

.005 

ih 

135 

411 

.007 

vi. 

150 

762 

.006 

1 

150 

573 

.006 

IX 

135 

342 

.008 

1 

150 

673 

.007 

1¥ 

135 

411 

.007 

\% 

135 

294 

.008 

13i 

135 

411 

.008 

iH 

135 

342 

.008 

2 

120 

228 

.009 

\yi 

135 

342 

.009 

1?4 

135 

294 

.008 

23-4 

120 

204 

.009 

m 

135 

294 

.009 

2 

120 

228 

.009 

2X 

120 

183 

.010 

2 

120 

228 

.010 

2  k. 

120 

204 

.009 

3 

120 

153 

.010 

2h 

120 

204 

.010 

2X 

120 

183 

.010 

3X 

120 

131 

.010 

2% 

120 

183 

.010 

3 

120 

153 

.010 

4 

120 

114 

.010 

3 

120 

153 

.010 

3X 

120 

131 

.010 

4X 

120 

102 

.010 

Table  1G.  —  Speeds  and  Feeds  for  Screw  Machine  Work 


SPEEDS   AND   FEEDS  FOR  TURNING 


165 


SPEEDS  AND  FEEDS  FOR  HOLLOW  MILLS.            SCREW  STOCK. 

3:,  Inch  Chip 

Yg  Inch  Chip 

Ja'   In  Oil  Chip 

Dia. 

of 

Stock 

Feet 
Surface 

Speed 

Rev.        Feed 
per          per 
Min.         Rev. 

Dia. 
of 

Stock 

Feet 
Surface 

Speed 

Rev. 
per 
Min. 

Feed 
per 
Rev. 

Dia. 
of 

Stock 

Feet 
Surface 
Speed 

Rev. 
per 
Min 

Feed 
per 
Rev. 

^B 

80 

2445        .0026 

\ 

60 

916 

.0045 

U 

55 

560 

.0052 

^16 

70 

1426 

.0039 

3j 

60 

611 

.0052 

H 

55 

420 

.0065 

H 

70 

1069 

.0052 

)4 

60 

458 

.0035 

% 

55 

280 

.0078 

li 

70 

713 

.0065 

J' 

55 

230 

.0078 

1 

50 

191 

.0091 

y. 

60 

458 

.0078 

1 

55 

210 

.OOGl 

1« 

50 

152 

.0091 

■ii 

60 

3(j5 

.0091 

1'4 

55 

168 

.0091 

1>6 

45 

114 

.0091 

1 

60 

229 

.0104 

L^i 

50 

127 

.0104 

Hi 

45 

93         .0091 

i'.t 

60 

183 

.OlOi 

w 

50 

109 

.0104 

2 

40 

76 

.0104 

\)4 

50 

127 

.0117 

2 

45 

86 

.0117 

2>i 

40 

68 

.0104 

l?i 

50 

109 

.013 

2;^ 

45 

76 

.0117 

2}i 

40 

61 

.0104 

2 

50 

95 

.013 

2>^ 

45 

68 

.0117 

3 

40 

51 

.0104 

23-4: 

50 

85 

.013 

3 

45 

57 

.0117 

3>^ 

! 

Ji's  Inch  Chip 

Ji  Inch  Chip 

?8   Inch  Chip 

Dia. 

of 

Stocli 

Feet 
Surface 
Speed 

Rev. 
per 
Min. 

Feed 
per 
Rev. 

Dia. 

of 

Stoclc 

Feet     '      Rev. 
Surface        per 
Speed        Min. 

Feed 
per 
Rev. 

Dia. 

of 

Stock 

Feet 
Surface 
Speed 

Rev. 
per 
Min. 

Feed 
per 
Rev. 

Yz 

55 

420 

.0052 

X 

50           254 

.0052 

1^4 

45 

137 

.0065 

3x 

55 

280 

.0065 

1 

50            191 

.003.5 

\W 

45 

114 

.0065 

1 

55 

210 

.0065 

lii 

45 

137 

.0066 

IK 

45 

93 

.0065 

1¥ 

50 

152 

.0078 

\yi 

45 

114 

.0078 

2 

40 

76 

.0078 

l>i 

50 

127 

.0078 

i?i 

45 

93 

.0078 

234 

40 

68 

.0078 

1?4 

50 

109 

.0078 

2 

40 

76 

.0078 

2H 

40 

61 

.0078 

2 

40 

76 

.0091 

234 

40 

68 

.0091 

3 

40 

51 

.0078 

2M 

40 

68 

.0091 

2>i 

40 

61 

.0091 

2>^ 

40 

61 

.0091 

3 

40 

51 

.0091 

1 

3 

40 

51    !    .0091 

i                ' 

' 

Table  17.  —  Speeds  and  Feeds  for  Screw  Machiue  Work 


166 


SPEEDS  AND   FEEDS  FOR   SCREW    MACHINE   WORK 


tools  the  feeds  are,  of  course,  increased  as  the  diameter  of  the  stock 
increases,  the  peripheral  speeds  being  reduced  as  the  feeds  grow  coarser 
and  the  chip  greater  in  depth. 

The  speeds  and  feeds  for  finishing  box  tools  as  used  on  different  mate- 
rials are  given  in  Table  18,  the  last  column  indicating  the  amount  of 
stock  which,  generally  speaking,  it  is  advisable  to  remove  in  order  to  pro- 
duce a  good  surface. 


CUTTING  SPEEDS  AND  FEEDS  FOR  FINISH  BOX  TOOL 

•-3 

Screw  Stock 

Brass  Rod 

Cast  Iron 

Tool  Steel 

Feet 
Surface 
Speed 

Rev. 
per 
Miu. 

Feed 
per 
Rev. 

Feet 
Surface 
Speed 

Rev. 
Ijer 
Miu. 

Feed 
per 
Rev. 

Feet 
Surface 
Speed 

Rev. 
per 
Mill. 

Feed 
per 
Rev. 

Feet 
Surface 
Speed 

Rev. 
per 
Min. 

Feed 
per 
Rev. 

>f6 

80 

4889 

.003 

180 

11000 

.003 

40 

2445 

.002 

.002 

'A 

80 

2445 

.0045 

180 

5500 

.0045 

40 

1222 

.003 

.0025 

5-16 

70 

1426 

.0055 

180 

3668 

.0055 

70 

1426 

.0055 

40 

815 

.003 

.0025 

« 

65 

993 

.0075 

180 

2750 

.0075 

70 

106t 

.0075 

35 

581 

.004 

.0045 

% 

60 

458 

.011 

180 

1375 

.011 

65 

496 

.011 

35 

267 

.005 

.006 

X 

60 

305 

.012 

180 

917 

.012 

65 

331 

.012 

35 

178 

.007 

.006 

1 

60 

229 

.012 

175 

668 

.012 

60 

229 

.014 

30 

115 

.009 

.0065 

1>^ 

55 

140 

.014 

170 

433 

.014 

60 

153 

.016 

30 

76 

.009 

.007 

2 

50 

95 

.014 

170 

325 

.014 

60 

115 

.016 

30 

57 

.009 

.008 

Table  18.  —  Speeds  and  Feeds  for  Screw  Machine  Work 


FORMING-TOOL    SPEEDS    AND    FEEDS 

Speeds  and  feeds  for  forming  tools  are  given  in  Table  19,  the  widths 
covered  here  ranging  from  -^^  inch  to  2  inches,  and  the  smallest  diameter 
of  form  from  \\  inches  down  to  xV  inch.  It  will  be  seen  that  the  tool 
about  ^r  inch  wade  is  adapted  to  take  the  coarsest  feed,  tools  from  this 
width  up  to  about  fV  (such  as  are  commonly  employed  for  cutting-off 
purposes)  admitting  of  heavier  crowding,  as  a  rule,  than  either  the  nar- 
rower or  wider  tools.  Thus  we  see  the  rate  of  feed  drop  off  as  the  tool 
narrows  to  yV  inch,  which  obviously  is  too  thin  a  cutting  device  to  admit 
of  taking  much  of  a  chip,  while  similarly  as  the  width  of  form  and  chip 
increases  above  about  ^^  or  \  inch  the  rate  of  feed  must  again  be  dimin- 
ished to  give  the  best  results.  Naturally,  other  things  being  equal,  the 
greater  the  diameter  of  the  section  formed,  the  coarser  the  feed  which 
can  be  taken  economically.  This  is  also  indicated  by  the  figures  in  the 
table. 

DRILLING    AND    REAMING    DATA 

Drilling  speeds  and  feeds  are  given  in  Table  20.  While  these  speeds 
are  based  on  much  higher  peripheral  velocities  than  drillmakers  as  a  rule 


DRILLING   AND    REAMING    DATA 


167 


recommend  for  general  purposes,  it  should  be  remembered  that  conditions 
for  drilling  in  the  automatic  on  the  usual  run  of  work  are  nearly  ideal  so  far 
as  lubrication  of  drill  and  work,  steadiness  of  feed,  etc.,  are  concerned,  and 
it  is  possible  under  these  conditions  where  the  holes  drilled  as  a  rule  are 


SPEEDS  FOR  FORMING 

Dla. 

of 
Work 

Screw  Stock 

Brass  Rod 

Cast  Iron 

Tool  Steel 

Feet 
Surface 

Speed 

Rev. 
per 
Min. 

Feet 
Surface 
Speed 

Kev. 
per 
Min, 

Feet 
Surface 
Speed 

Rev, 

per 
Min. 

Feet 

Surface 

Speed 

Rev. 
per 
Min, 

H 

75 

2292 

200 

6112 

H^ 

75 

1528 

200 

4074 

'4 

70 

1063 

185 

2827 

75 

1146 

45 

688 

% 

65 

662 

185 

1885 

70 

713 

40 

407 

H 

C5 

497 

185 

1414 

70 

535 

40 

306 

K 

60 

305 

175 

882 

65 

331 

35 

178 

1 

60 

229 

175 

667 

65 

248 

35 

134 

1>6 

60 

153 

170 

432 

60 

153 

30 

76 

o 

50 

96 

170 

324 

60 

115 

30 

57 

FEEDS  FOR  FORMING  TOOLS 

With 

of 
Form 

SmaUest    Diameter  of   Form. 

'4 

-16 

M 

X 

y^ 

X 

1)4 

'-16 

.0007 

.0008 

.001 

.0012 

.0012 

,0012 

,0012 

,0012 

li 

.0005 

.0008 

.001 

.0012 

.0015 

.0020 

.0025 

.0025 

H 

.0007 

.001 

.001 

,0015 

,0015 

.0018 

.0018 

?3 

.0009 

.001 

,001 

.0012 

.0015 

.0015 

}i 

.0008 

.0009 

.001 

,001 

.0015 

.0015 

X 

.0008 

.0009 

.001 

.0011 

.0012 

1 

.0008 

.0009 

.001 

,0012 

\>i 

.0007 

.0007 

,0009 

,0011 

2 

.0007 

.001 

Table  19.  —  Speeds  and  Feeds  for  Screw  Machine  Work 

comparatively  shallow  and  the  drill  has  ample  opportunity  for  cooling  dur- 
ing the  operations  carried  on  by  the  other  tools,  to  maintain  speeds  that 
would  be  considered  too  high  to  be  attempted  in  general  shop  practice. 
Table  21  is  made  up  of  speed  and  feed  data  for  reamers.     In  this  table 


168 


SPEEDS  AND  FEEDS   FOR  SCREW  MACHINE  WORK 


•— I— it,"\ea5'n'"^*'CEJuu  w 


Q 

Ph 

m 
Q 

xn 

Q 

ft 

o 

o 

K.P.M. 

at 
33  Ft. 
Peri- 
pheral 
Speed 

8 

g 

CO 

2 

*31 

CO 

£ 

s 

2 

g 

s 

CO 

g 

CO 

no 

1^  s 

t- 

CO 

CD 

1 

C5 

3 

CO 

CD 

O 

CO 

i 

1 

o 
o 

i 

o 

i 

cs 

2 

p 

o 

cS 

O 

0-      'nA^'g^cn 

1 

i 

^5 

i 

8 

i 

o 

Si 

g 

<:» 

1 

2 

1 

00 

OS 

CO 

OS 

1^    o 

3 

1 

c:5 

t:- 

s 

s 

8 

8 

O 
CD 

CD 

CD 

g 

CO 

i 

o 
o 

CD 

CI 

p 

CO 

p 

p 

o 

01 

7! 

1 

to 

s 

o 

53 

o 

3 

g 

i 

CO 

CO 

in 

1 

CO 

1 

t- 

^ 

3 

|i(  -^  M 

i 

^ 

t* 

t- 

8 

8 

i 

1 

o 

CO 

o 
CO 

o 

p 

CO 
p 

CO 
in 

p 

s 

p 

2 

p 

o 

M 

CD 
O 

m 

i 

Si 

CO 

i 

i 

i 

O 

SI 

Ol 

s 

ca 

05 
CO 

2 

05 
CO 

Ol 

00 

2 

^ 

fe  -  « 

i. 

CO 

1 

8 

i. 

CD 

i 

00 

1 

8 

i 

CD 

o 

CD 

p 

CO 

p 

•* 
p 

5°5 

:.^ 

;t 

/^ 

i= 

-2 

.- 

v2 

^? 

-2 

- 

a." 

5 

S 

2 

S 

H 

(M 

(D 

m 

o 
o 

oj 

CM 

CO 

i 

i 

1 

i 

CO 

CO 

8 

s 

-* 

i 

s 

i 

c:^ 

i 

o 
o 

CD 

8 

o 

CD 

lO 

i 

i 

• 

CO 

8 

CO 

8 

o 
o 

i 

i 

t- 

o 

CO 

^ 

S 
^ 

t- 

i 

5; 

2 

00 

00 

■» 

C>J 

00 

3 

CO 
c^ 

00 

S 

f^  °'  « 

<3 

o 

o 

C3 

CO 

o 

CO 

8 

o 

CD 

1 

lO 

i 

i 

8 

3 

CD 

iCI 

3 

CD 

3 

CD 

lO 

3 
p 

o 

IS 
o 

CO 

fc  ^  JO  S  o   S, 

o 

CO 

1 

1 

o 

c» 

i 

00 

CO 

iCI 

1 

ot 

t- 

1 

1 

i 

00 

CO 

o 

o 

8 

1 

co 

CO 

CO 

i 

8 

CD 

8 

1 

i 

00 

8 
p 

p 

o 

o 
o 

•  «  En   L,   "    (B 

i- 

o 

88 

-7* 

35 

t- 

i 

in 

2 

CO 

2 

00 

c:^ 

1 

00 
o 

i 

CO 

i 

Is  £ 

fe  ^  M 

CD 

i 

8 

CO 

8 

«o 

00 

s 

8 

<D 

i 

CO 

i 

1 

UO 

3 

CO 

3 

p 

o 

i 

5°a 

•A 

- 

i 

i 

1 

s 

i? 

s 

i" 

„- 

;^ 

^t 

^ 

Is- 

i? 

^\ 

THREADING,    COUXTERBORIXG,    ETC. 


169 


the  feed  for  different  classes  of  material  has  been  considered  as  constant 
for  any  given  diameter  of  reamer,  although  it  is  conceivable  that  with 


REAMING    FEEDS  AND    SPEEDS 

5  X. 

Feed 
per 
Rev. 

Amount 

to 
Remove 

on 
Dia. 

Rev.  per  Mil. 

5  il 

Feed 
per 

Rev. 

Amount 

to 

Remove 

on. 

Dia. 

Rev.  per  Min.              1 

Screw 
Stock 

at 
40  Ft. 

Brass 

Rod 

at 

130  Ft. 

Cast        Tool 
Iron        Steel 

at              at 
45  Ft.      2.5  Ft. 

Screw 
Stock 

at 
40  Ft. 

Brass 
Rod 

at 
130  Ft. 

Cast 
Iron 

at 
45  Ft. 

Tool 
Steel 

at 
25  Ft. 

h 

,005 

.0045 

1222 

3972 

1375 

764 

lU 

.018 

.010 

122 

397 

138 

76 

3- 
--IS 

.006 

.0045 

815 

2648 

917 

509 

l^ 

.020 

.010 

102 

331 

115 

63 

H 

.007 

.006 

611 

1986 

688 

382 

1J4 

.022 

.010 

87 

284 

98 

54 

?8 

.0085 

.006 

407 

1324 

458 

254 

2 

.024 

.013 

76 

248 

86 

48 

}i 

.0105      .008 

306 

993 

344 

191 

2Ji 

.026 

.013 

68 

220 

76 

42 

% 

.012        .008 

245 

795 

275 

153 

2X' 

.028 

.013 

61 

199 

69 

38 

% 

.014        .008 

204 

662 

229 

127 

2% 

.030 

.013 

56 

181 

63 

35 

\ 

.016 

.010 

153 

497 

172 

95 

3 

.032 

.013 

51 

165 

57 

32 

Table  21.  —  Si^eeds  and  Feeds  for  Screw  ^lachine  Work 

certain  materials,  especially  on  brass  alloys,  etc.,  the  feed  per  revolution 
might  be  increased  somewhat,  to  advantage,  over  the  rates  given.  These 
feeds  have  been  tabulated,  however,  as  representing  highly  satisfactory 
practice  in  reaming  the  materials  listed. 


SPEEDS  FOR  DIES  -  STANDARD  THREADS. 

Dia. 

of 

Thread 

Screw  Stock 

Brass  Rod 

Cast  Iron 

Tool  Steel 

Cast  Brass 

Feet 
Surface 
Speed 

Rev. 
per 
Min. 

Feet 
Surface 
Speed 

Rev. 
per 
Min. 

Feet           Rev. 

Surface         per 

Speed         Min. 

Feet          Rev. 

Surface         per 

Speed         Min. 

Feet 

Surface 

Speed 

Rev. 
per 
Min. 

a 

40 

1222 

135 

4126 

40 

1222 

25 

764 

120 

3666 

¥ 

40 

611 

125 

1909 

40 

611 

25 

382 

110 

1680 

?3 

35 

356 

120 

1222 

35 

356 

20 

204 

100 

1019 

}i 

35 

267 

120 

917 

35 

267 

20 

153 

100 

764 

K 

35 

178 

115 

586 

30 

153 

20 

102 

100 

509 

1 

30 

115 

110 

420 

30 

115 

20 

76 

90 

344 

IK 

30 

92 

lOO 

3C6 

25 

76 

15 

46 

90 

275 

1^ 

30 

76 

90 

229 

25 

64 

15 

38 

90 

229 

2 

25 

48 

85 

162 

20 

38 

15 

29 

00 

172 

Table  22.  —  Speeds  and  Feeds  for  Screw  Machine  ^^'ork 
THREADING,    COUXTERBORIXG,    ETC. 

Table  22  explains  itself  and,  while  giving  speeds  for  threading  work 
with  dies,  should  be  of  equal  value  in  establishing  speeds  for  tapping.     It 


170  SPEEDS  AND  FEEDS  FOR  SCREW  MACHINE  WORK 

should  be  noted  that  the  speeds  in  this  table  are  proper  for  high  speed 
dies.  For  carbon  steel  dies  the  speeds  used  should  be  from  50  to  75  per 
cent  of  the  rates  given. 

For  feeds  for  counterbores  from  |  inch  to  2  inches  diameter,  Tables 
15  and  16  for  turning  may  be  followed  where  the  counterbores  cut  to  a 
depth  from  one-half  to  three-quarters  their  diameter.  Where  cutting 
deeper  than  about  one  diameter,  the  feeds  should  be  decreased;  in  such 
depths  it  is  well  to  withdraw  the  counterbore  during  the  cutting  opera- 
tion to  free  it  from  chips. 

It  is  not  expected  that  the  speeds  and  feeds  laid  down  in  these  tables 
will  coincide  exactly  with  the  ideas  of  everybody  engaged  in  screw  machine 
operations.  Conditions  as  to  materials,  lubricants,  clearances  of  cutting 
edges,  quality  of  tools,  etc.,  all  have  an  important  bearing  upon  the  ques- 
tion of  efficient  cutting  speeds  and  feeds.  It  is  believed,  however,  that 
the  foregoing  information  should  be  of  service  to  a  good  many  readers, 
representing  as  it  does  the  practice  commonly  followed  by  one  of  the  largest 
tool  shops  with  its  carbon-steel  screw  machine  tools. 


CHAPTER   XXI 

Spring  Collets  and  Feed  Chucks 

Spring  collets  and  feed  chucks  or  feed  fingers  as  they  are  frequently 
called,  are  the  first  tools  to  be  considered  in  connection  with  screw  machine 
work  as  upon  these  appliances  devolve  the  operations  of  feeding  the  bar  of 
material  through  the  spindle  and  the  holding  of  it  while  the  different 
machining  cuts  are  taken  by  the  various  cross-slide  and  turret  tools. 

When  manufactured  in  large  quantities  the  collet  blanks  are  produced 
in  the  turret  machine  by  the  aid  of  forming  tools  for  machining  the  ex- 
terior surface  and  by  suitable  internal  tools  of  the  drill  and  reamer  order 
for  finishing  the  interior  to  the  required  dimensions.  In  making  a  few 
collets  at  a  time,  however,  as  is  generally  the  practice  in  the  smaller  shops, 
a  few  simple  appliances  suffice  for  the  satisfactory  handling  of  the  work 
during  the  different  operations. 

LATHE    OPERATIONS 

The  collet  blank  may  first  be  roughed  out  in  the  lathe  and  the  inside 
chucked  out  and  reamed  taper  from  the  rear  end  to  leave  the  walls  of  the 
collet  body  of  suitable  proportions  and  to  allow  the  collet  to  be  slipped 
onto  a  taper  arbor  the  rear  end  of  which  is  fitted  to  the  taper  hole  in  the 
lathe  spindle.  While  mounted  on  this  arbor  the  outer  end  of  the  collet 
is  centered  and  center  reamed  to  allow  it  to  be  supported  by  the  tail  center, 
and  the  body  may  then  be  turned  and  bored  to  correct  shape  and  size 
without  removing  from  the  arbor.  It  is  sometimes  advantageous  to  rough 
out  two  collets  on  the  same  piece  of  stock  and  then  cut  apart  and  mount 
on  the  taper  plug  arbor  for  finishing  separately.  This  method  gives  a 
longer  and  handier  piece  of  material  to  work  in  the  lathe. 

The  work  is  readily  removed  from  the  taper  arbor  on  which  it  is  turned, 
by  means  of  a  nut  on  a  threaded  portion  of  the  arbor  body  adjacent  to 
the  taper  section.  Before  taking  the  chuck  blank  off  from  its  arbor  the 
conical  nose  should  be  gaged  carefully  to  make  sure  that  it  will  fit  prop- 
erh  in  its  seat  in  the  screw  machine  spindle.  The  hole,  bored  in  the  front 
end  for  the  bar  material,  should  be  true  and  straight  —  especially  if  grind- 
ing is  not  to  be  resorted  to  after  hardening.  Of  course  where  absolute 
truth  is  essential  in  the  running  of  the  collet  it  is  important  that  the  hole 
be  ground  after  hardening  with  the  collet  seated  in  a  grinder  fixture  in 
precisely  the  same  way  as  it  will  later  be  operated  in  the  screw  machine. 

171 


172  SPRING   COLLETS   AND   FEED   CHUCKS 


HOLDING    WHILE    SLITTING 

The  taper  arbor  referred  to  is  of  the  general  form  indicated  in  Fig. 

153,  which  shows  the  method  also  of  carrying  the  work  between  the 
dividing  head  and  tail  center  on  the  milling  machine,  while  the  slots 
are  being  cut  to  allow  the  collet  to  open  and  close  on  the  material  when 
in  service.  There  are  numerous  methods  of  mounting  collets  for  this 
slitting  operation,  but  the  one  indicated  is  as  simple  as  any  and  entirely 
satisfactory  where  collets  are  put  through  in  small  lots  and  more  elaborate 
fixtures  are  therefore  uncalled  for.  If  a  small  piece  of  flat  stock  is  cen- 
tered as  shown  and  introduced  between  the  end  of  the  work  and  the 
foot  center  of  the  dividing  head,  and  the  center  itself  flatted  on  top,  suffi- 
cient clearance  will  be  obtained  for  the  slitting  saw  which  is  run  into  the 
work  from  the  front  end. 

COLLET    INTERIOR 

It  is  well  to  shape  the  interior  of  the  collet  about  as  illustrated  in  Fig. 

154,  the  long  curve  or  fillet  b  at  the  front  end  of  the  chamber  where  it 
joins  the  cylindrical  hole,  forming  in  conjunction  with  the  fillet  at  a  a 
strong  section  not  likely  to  break  away  in  the  operation  of  the  collet. 
The  internal  sloping  surface  at  b  also  facilitates  the  passing  of  a  fresh 
bar  of  stock  into  the  collet  upon  the  finishing  up  of  the  previous  length 
of  material. 

PREPARING    FOR    HARDENING 

Before  hardening  collets  it  is  common  practice  to  open  them  somewhat 
to  insure  their  having  a  given  tension  after  hardening  and  tempering  so 
that  they  will  open  and  release  the  stock  the  instant  they  are  themselves 
freed  by  the  cam-operated  chucking  mechanism.  This  opening  of  the 
collet  must  be'  carefully  attended  to  or  an  eccentric  and  unsatisfactory 
job  will  be  the  result.  Sometimes  a  simple  fixture  having  a  cone-pointed 
spindle  is  used  for  this  purpose,  the  collet  or  chuck  being  held  centrally 
while  the  cone  plunger  is  forced  between  the  chuck  jaws  sufficiently  to 
open  them  evenly  the  necessary  amount.  However,  no  matter  how 
much  care  is  taken  in  this  operation,  the  effect  is  lost  unless  the  harden- 
ing is  properly  attended  to,  and  the  only  sure  way  of  producing  a  per- 
fectly true  collet  with  certainty  is  to  grind  it  as  a  final  operation. 

PREVENTING    DISTORTION 

Some  toolmakers  take  the  precaution  of  leaving  a  thin  fin  of  metal  at  the 
front  end  of  the  collet  in  each  saw  slot,  as  in  Fig.  155,  in  order  that  when 
hardened  there  shall  be  no  chance  of  distortion  due  to  unequal  springing 
of  the  prongs  or  jaws.  This  metal  tie  or  bridge  at  the  ends  of  the  jaws  is 
readily  removed  by  grinding  out  with  a  thin  slitting  wheel  or  lap.  Still 
another  scheme  is  illustrated  in  Fig.  156,  which  comprises  in  addition  to 


PREVENTING   DISTORTION 


173 


o 

be 


Oh 


174  SPRING  COLLETS  AND  FEED  CHUCKS 

the  thin  wall  of  metal  at  the  front  ends  of  the  saw  slots,  a  narrow  ring  or 
nose  adapted  to  be  carried  on  a  grinder  center  while  the  collet  is  ground 
externally.  Thus  inequalities  introduced  in  the  hardening  process  may  be 
rectified  by  grinding  and  afterward  the  superfluous  metal  at  the  end  of  the 
collet  nose  may  be  ground  off  leaving  the  appliance  ready  for  service. 

Another  method  of  preventing  trouble  in  hardening  collets  is  to  insert 
a  piece  of  sheet  metal  (say  ^V  inch  thicker  than  the  slot  width)  in  the 
front  ends  of  the  slots  and  then  wire  the  nose  of  the  chuck  tightly  so  as 
to  retain  the  steel  pieces  during  the  hardening  operation.  The  collet 
must  be  heated  uniformly  and  dipped  so  as  to  insure  all  three  prongs 
being  cooled  simultaneously,  otherwise  they  will  be  of  different  lengths 
and  twisted,  resulting  in  an  untrue  collet.  With  the  best  of  care,  a  collet 
that  is  hardened,  but  not  ground  afterward,  will  generally  require  touching 
up  on  the  conical  portion  of  one  or  two  of  the  prongs  to  insure  its  running 
true.  It  is  not  a  difficult  undertaking,  however,  to  make  a  chuck  run 
true  within  0.002  inch  by  polishing  one  or  two  prongs. 

In  order  that  the  collet  may  close  parallel,  it  must  be  fairly  long,  and 
the  exterior  of  each  prong,  or  jaw,  may  be  relieved  by  filing,  as  in  Fig. 
157,  so  as  to  insure  its  bearing  along  the  center.  After  hardening,  the 
collet  should  be  carefully  tempered  at  the  ends  of  the  slots  to  prevent 
breaking  at  this  point. 

FEED    CHUCKS 

The  feed  chucks  or  feed  fingers  need  no  such  refinements  in  their  pro- 
duction. They  are  usually  closed  after  slitting  on  opposite  sides,  and 
thus  after  hardening  they  will  maintain  a  constant  grip  upon  the  stock 
sufficient  to  feed  the  bar  forward  the  moment  it  is  released  by  the  chuck. 
The  idea  is  indicated  in  Fig.  158,  which  represents  a  typical  feed  chuck. 
Ordinarily  the  liole  for  the  stock  should  be  bored  out  a  little  over  size, 
otherwise  the  corners  of  the  feed  chuck  jaws  when  drawn  back  over  the 
stock  will  mar  the  surface. 

A    GRINDING    FIXTURE    FOR    CHUCKS 

A  handy  grinding  appliance  for  spring  collets  is  shown  in  Fig.  159, 
this  sketch  being  made  from  a  device  in  use  at  the  E.  Howard  Watch 
factory,  Waltham,  Mass.  This  particular  tool  is  adapted  to  receive  an 
automatic  screw  machine  collet  after  it  is  hardened,  and  hold  it  during 
the  grinding  operation  in  precisely  the  same  manner  in  which  it  will  later 
be  held  in  the  screw  machine  when  in  operation.  The  quill  in  which  the 
spindle  is  carried  is  slipped  into  a  regular  quill  rest  on  the  bench  lathe 
or  grinder,  and  the  collet  to  be  ground  out  is  readily  inserted  and  as  easily 
removed  when  the  grinding  or  lapping  operation  is  completed. 

All  parts  of  this  fixture,  including  quill,  spindle,  rear  bearing,  cone, 
cap,  and  adjusting  nut,  are  of  steel,  hardened,  ground  and  lapped. 


CHAPTER  XXII 

.   Box  Tools  and  Other  External  Cutting  Appliances 

The  accompanying  engravings,  Figs.  160  to  179,  illustrate  a  variety 
of  so  termed  box  tools  and  hollow  mills  which  are  used  in  automatic 
screw  machines,  and  in  much  the  same  form  in  hand  machines  also.  It  is 
the  purpose  of  this  chapter  to  point  out  some  of  the  reasons  for  different 
designs  and  to  show  for  what  particular  cases  each  type  of  tool  illustrated 

is  best  adapted. 

general  principles 

Practically  all  box  tools  consist  primarily  of  a  frame  or  body  which 
is  clamped  to  the  turret  of  the  screw  machine.  The  box-tool  frame  is 
utilized  for  holding  the  cutting  tools  and,  usually,  a  work-supporting 
device  commonly  known  as  a  back  rest.  In  the  frame  there  is  also  in 
some  instances  provision  made  for  holding  internal  cutting  tools  such  as 
drills,  counterbores,  etc.;  in  this  latter  case  outside  turning  and  boring 
may  be  accomplished  simultaneously.  The  cutting  tools  are  usually 
adjustable  so  as  to  be  suitable  for  turning  various  diameters;  the  back 
rests  or  w^ork-supporting  devices  are  made  both  adjustable  and  solid  or 
non-adjustable.  Both  cutting  tools  and  back  rests  are  preferably  mounted 
in  sub-holders  permitting  of  longitudinal  adjustment.  The  most  com- 
mon turning  tools  in  use  are  for  cylindrical  work,  but  taper  work  can  also 
be  successfully  produced  by  box  tools  designed  for  the  purpose. 

CONDITIONS    OF    SERVICE 

The  type  of  box  tool  in  general,  as  well  as  such  features  as  the  work- 
supporting  device  and  the  manner  in  which  the  cutting-tool  edge  is  pre- 
sented to  the  work,  are  dependent  upon  various  conditions,  among  which 
may  be  mentioned: 

1.  Length  of  work  being  turned; 

2.  Uniformity  of  diameter  of  stock  used  (bright  drawn  or  rough 
stock); 

3.  Cross-section  of  stock  (circular  or  otherwise) ; 

4.  Character  of  material; 

5.  Reduction  in  diameter  to  be  made; 

6.  Character  of  longitudinal  cut  (cylindrical,  taper,  or  other). 
Before  explaining  the  reasons  why  the  foregoing  conditions  should 

175 


176       BOX   TOOLS   AND    OTHER   EXTERNAL   CUTTING   APPLL\NCES 

influence  the  design  of  tool,  it  may  be  well  to  understand  precisely  by 
name  the  various  parts  which  are  frequently  referred  to  later  on.  To 
this  end  a  few  of  the  different  types  of  box  tools  and  component  parts, 
as  shown  by  Figs.  160  to  167,  will  first  be  briefly  described. 

TYPES    OF    BOX    TOOLS 

Figs.  160  and  161  illustrate  a  box  tool  with  movable  blocks  holding 
the  cutters  and  with  a  back  rest  of  the  non-adjustable  open  type.  The 
cutting  edge  of  the  tool  is  practically  radial,  but  longitudinally  the  cutter 


Fig.  160. 


Non- Adjustable  Roughing  Box 
Tool 


lies  tangent  to  the  circle  representing  the  work.  This  tool  is  commonly 
called  a  roughing  box  and  is  recommended  for  heavy  cuts  as  there  is  less 
danger  of  springing,  due  to  the  strain  on  the  tool  in  cutting,  than  in  the 
case  of  the  radial  tool  in  Figs.  162  and  163.     The  latter  tool  has  movable 


Fig.  1(52.  —  Adjustable  Finishing  Box  Tool 

blocks  holding  the  cutters,  and  movable  blocks  carrjdng  the  back-rest 
jaws.  Both  cutters  and  back-rest  jaws  may  be  adjusted  to  suit  different 
diameters  of  work.  The  cutting  edge  of  the  cutter  is  radial  to  the  work 
and  is  parallel  with  the  longitudinal  section  of  the  cutter.     The  tool  is 


TYPES  OF   BOX  TOOLS 


177 


'. — ] 

f4 

L 

_j  \- 

/              1 

rjv      V;.>;v:T,r,r,r7;;iri,T. 
-1  y'   ^'|i.i"i'D'!i''j'i'i;'', 

1 

J 

te-  rx 

V 

178       BOX   TOOLS   AND   OTHER    EXTERNAL   CUTTING   APPLL\NCES 

used  mostly  for  brass  and  similar  material  and  for  light  cuts  on  steel,  and 
is  in  this  general  form  commonly  known  as  a  finishing  box.  On  very 
free-cutting  materials  such  as  brass,  the  edge  of  the  cutting  tool  is  generally 
presented  to  the  work  without  any  rake,  as  shown  in  Fig.  163.  In  cut- 
ting the  harder  materials,  steel,  etc.,  and  especially  in  taking  roughing 
cuts  on  such  material,  rake  is  desirable;  hence  the  tool  of  the  roughing 
box  is  presented  to  the  work  in  the  manner  shown  by  Fig.  161. 

The  tangent  cutter  used  in  the  box  tool  shown  in  this  view  and  in 
Fig.  160  is  sharpened  by  grinding  on  the  end,  and  compensation  for  the 
grinding  away  of  the  metal  is  made  by  adjusting  the  cutter  forward, 
whereas  in  the  radial  type  of  cutter  in  Figs.  162  and  163,  frequent  sharpen- 
ing cannot  be  done  without  resulting  in  lowering  the  cutting  edge  of  the 
tool  below  the  center  of  the  work,  unless  a  substantial  part  of  the  tool 
be  sacrificed.  The  radial  tool,  however,  is  easily  ground  accurately  on 
face  a,  which  is  the  particular  edge  governing  the  finish;  while  the  corre- 
sponding face  on  the  tangent  type  of  tool  is  rather  difficult  to  grind  so 
as  to  produce  as  smooth  work. 

OTHER  FORMS  OF  BOX  TOOLS 

Fig.  164  outlines  the  general  scheme  of  a  box  tool  with  tangent  cutter 
having  means  of  radial  adjustment  for  various  diameters,  the  back  rests 
being  adjustable  also,  as  indicated. 

In  Fig.  165  we  have  a  box  tool  with  a  back  rest  of  the  bushing  type 


Fig.  16.5.  —  Bushing;  Box  Tool 


which  fully  envelops  the  work.  A  bushing  like  that  shown  in  Fig.  166 
is  frequently  used  in  the  bushing  type  of  box  tool.  This  bushing  is  tapered 
externally  and  drawn  into  a  conical  hole,  and  is  thus  suitable  for  slight 
variations  in  stock  sizes.  Fig.  167  shows  another  "solid"  rest,  but  with- 
out a  bushing.  The  question  of  chip  room  frequently  makes  it  neces- 
sary to  abandon  the  bushing  and  bore  the  hole  for  the  stock  directly  in 
the  back  rest.  Quite  often  the  back  rest  is  cut  away  to  allow  the  tools 
to  operate  on  a  second  shoulder  cut;  then  the  bushing  as  ordinarily  made 
interferes.  As  a  rule,  it  is  preferable  to  use  the  bushing  where  possible, 
owing  to  the  ease  with  which  it  may  be  replaced  when  worn  out  of  shape, 


SELECTION   OF    BACK   RESTS 


179 


and  also  because  of  the  facility  with  which  anv  chano;es  due  to  hardenino- 
may  be  corrected. 

Other  types  of  work-supporting  devices,  such  as  internal  stem  rests, 
etc.,  are  very  commonly  used.  Fig.  168  illustrates  such  a  combination. 
Frequently,  too,  revolving  stem  rests  are  used  in  place  of  the  stationary 
type  shown.  Quite  often  a  drill  or  counterbore  is  held  in  the  shank  of 
the  box  tool  in  a  similar  manner  and  acts  as  a  support,  and  also,  as  before 
stated,  enables  turning  and  boring  operations  to  be  accomplished  simul- 
taneously. 


FIG.  169.  Long  Work 


FIG.  I  66.  Bushing 


d 


0 


1 — ^-^■ 


b 


tdB 


FIG. 167 


Work 

:q 

^^■^^^■^-^ 

__-.\ 

i     ¥         1 

k 

i   V       rr-" 

. 

i 

1  '^ 

'  u 

) 

Shank 

FIG. 168 


Other  Turning  Methods 


SELECTION    OF    BACK    RESTS 

Generally  speaking,  work  that  projects  over  one  and  one-half  times 
its  diameter  from  the  spindle  chuck  cannot  be  turned  accurately  or  rapidly 
without  the  aid  of  a  support  which  will  prevent  the  work  springing  away 
from  its  proper  radial  relation  to  the  edge  of  the  cutting  tool. 

Usually  on  work  which  does  not  project  over  five  diameters  from 
the  chuck,  the  back  rest  is  located  so  as  to  support  the  work  by  the  diam- 
eter produced  by  the  first  cutting  tool  in  the  box  tool,  the  back  rest  being 
set  from  about  -g\  inch  to  ^V  ii^ch  back  of  the  cutting  tool,  as  in  Figs.  161 
and  16.3.  While  any  of  the  types  of  back  rests  shown  in  Figs.  160  to  167 
may  be  used,  on  w^ork  of  the  length  mentioned  an  enveloping  back  rest 
is  not  required.  The  type  of  back  rest  used  in  the  tool  in  Figs.  162  and 
163  is  adjustable  for  wear  and  preferable  on  this  account.  The  non- 
adjustable  open  back-rest,  Figs.  160  and  161,  is  recommended  only  when 
the  design  of  the  tool  makes  it  difficult  to  utilize  an  adjustable  type.  All 
back  rests  should  be  of  tool  steel.  They  should  be  very  hard  and  smooth; 
otherwise  when  used  on  fast-running  material  such  as  brass,  a  welding 
action  takes  place.  They  should  be  ground  and  lapped  on  the  bearing 
face  so  as  to  bear  more  strongly  on  the  forward  end  of  the  work  than  at 


180       BOX   TOOLS   AND   OTHER   EXTERNAL   CUTTING   APPLIANCES 

the  rear.  The  clearance  need  not  be  more  than  0.003  or  0.004  inch  to 
the  foot.  Should  the  back  rest  be  bell  mouth,  the  work  turned  will  be 
rough  and  covered  with  ridges. 

TOOL    POSITION,    LUBRICATION,    ETC. 

Also  it  is  quite  important,  where  using  such  rests,  that  the  work  be 
not  turned  too  large  if  roughing  up  of  the  surface  is  to  be  avoided.  About 
0.0005  inch  freedom  should  be  allowed  for  work  up  to  ^-inch  diameter, 
and  about  0.001  inch  freedom  for  1-inch  diameter.  Proper  lubrication 
of  the  bearing  is  also  essential  in  preventing  roughing  up  of  the  work. 
Lack  of  alinement  of  solid  or  half-open  rests  with  the  spindle  of  the 
machine  may  also  cause  the  production  of  poor  surfaces  on  the  work, 
owing  to  the  heavy  crowding  action  under  such  conditions. 

In  setting  adjustable  back-rest  jaws  it  will  be  found  conducive  to 
good  work  to  hold  a  bar  in  the  head  spindle,  turn  a  true  running  piece  of 
work  from  0.0004  inch  to  0.0008  inch  oversize  and  then  adjust  the  jaws 
so  that  they  will  bear  snugly  on  the  turned  part.  The  closer  this  is  to 
the  spindle  the  better.  In  using  solid  or  non-adjustable  open-back  rests, 
as  shown  by  Figs.  160,  161,  165,  and  167,  it  is  recommended  that  they  be 
bored  out  while  held  in  the  turret  hole  of  the  machine  that  they  are  to 
be  used  in.  This  insures  the  hole  being  in  alinement  with  the  head  spindle; 
these  conditions,  as  well  as  having  the  turret  slide  travel  parallel  with  the 
axis  of  the  head  spindle,  are  necessary  in  order  to  produce  accurate  work. 

Burnishing  of  stock  generally  results  from  the  pressure  of  the  cutting 
tool  forcing  the  work  against  a  closely  adjusted,  smooth  back  rest,  and  is 
usually  considered  an  evidence  of  proper  adjustment.  Frequently,  how- 
ever, this  is  found  not  to  be  the  case. 

LONG    AND    SHORT    W'ORK 

On  very  long  w^ork,  when  bright-drawn  cylindrical  stock  of  uniform 
diameter  is  being  turned,  the  solid  back  rest  is  found  very  satisfactory. 
The  rest  is  in  this  event  set  ahead  of  the  cutting  tool  and  fully  enveloping 
the  work.  It  obviously  prevents  any  tendency  for  the  work  to  spring 
away.  Where  heavy  stock  which  does  not  run  true  is  to  he  machined, 
it  is  necessary  before  turning  partly  to  cut  off,  as  shown  by  Fig.  169,  thus 
permitting  the  back  rest  to  pull  the  bar  into  central  position.  In  case 
there  are  short  bends  in  the  bar,  trouble  will  be  met,  so  that  for  long  work 
machined  in  this  manner  it  is  necessary  to  select  straight  bars.  It  is 
also  important  where  a  back  rest  is  used  ahead  of  the  cutting  tool  (that 
is,  where  the  unmachined  bar  rotates  directly  in  the  back  rest)  to  select 
practically  uniform  diameters  of  stock,  not  varying  in  size  over  0.0004 
inch  to  0.0008  inch.  In  many  large  screw  factories  all  bright-drawn 
stock  is  carefully  gaged  as  soon  as  received  and  sorted  out  in  this  manner; 


CAST-IRON  WORK 


181 


in  setting  up  the  machine  a  back  rest  is  selected  to  suit  a  particular  bundle 
of  gaged  stock. 

IRREGULARITY   OF    STOCK    SECTION 

Where  bright-drawn  stock  is  used  which  is  slightly  out  of  round,  as 
is  very  frequently  the  case,  the  use  of  a  full  enveloping  back  rest  preced- 
ing the  cutting  tool  will  be  found  superior  to  the  jaw  type,  giving  a  two- 
point  bearing.  In  the  former  case  the  pressure  of  the  tool  cannot  force 
the  work  away  and  the  turned  part  will  be  cylindrical;  whereas  with  the 
jaw  type  of  back  rest  the  pressure  of  the  cut  will  keep  the  irregular  con- 
tour of  the  bar  against  a  jaw  and  consequently  reproduce  a  similar  cross- 
section  to  the  turned  part.  This  emphasizes  the  value  of  using  back-rest 
jaws  so  as  to  follow  the  cutting  tool;  but  as  before  noted,  their  use  is  lim- 
ited to  short  work  and  work  of  medium  length.  In  such  work,  if  the  back- 
rest jaws  are  properly  set  and  the  turret  slide  travels  parallel  with  the 
axis  of  the  head  spindle,  true  work  will  result  irrespective  of  the  collet 
or  turret  hole  being  out  of  line  with  the  spindle. 

CAST-IRON    WORK 

In  machining  cast  iron,  as  on  the  magazine  automatic,  box  tools  with 
the  ordinary  types  of  rests  are  not  satisfactory,  owing  to  the  fact  that 
the  cast-iron  dust  is  apt  to  l^ecome  ground  between  the  rest  jaws  and  the 
turned  part  of  the  work,  thus  causing  the  latter  to  become  roughed  up. 
The  use  of  water,  however  (with  just  enough  oil  to  prevent  rusting),  or 
any  thin  solution  under  pump  pressure,  effectually  overcomes  this  trouble; 
oil  seems  to  increase  the  difficultv. 


^ 

^ 

^^^g^sl 

fe^ 

^w^2^^ 

S'«l 

^^ 

p^ 

Fig.  170.  —  Box  Tool  with  Roller  Rest 

A  box  tool  with  roller  back  rests,  which  is  excellent  on  cast-iron  work 
when  used  in  conjunction  with  an  air  blast  to  keep  dust  from  accumulating 
between  the  rollers  and  work  surface,  is  shown  in   Fig.  170.     This  box 


182       BOX   TOOLS   AND    OTHER   EXTERNAL   CUTTING   APPLIANCES 


tool  as  sometimes  used  on  the  Pratt  &  Whitney  magazine  machine,  may- 
be stiffly  supported  at  the  bottom  by  a  hardened-steel  plate  carried  on  a 
bracket  attached  to  the  front  end  of  the  turret  slide  and  traveling  with 
the  slide.  Another  satisfactory  way  of  turning  cast  iron  is  by  means  of 
hollow  mills. 

HOLLOW    MILLS 

Hollow  mills  are  also  very  suitable  for  turning  long  work  from  bar 
stock.  These  tools  with  multiple  teeth  support  the  work  centrally,  cut 
very  rapidly,  and  if  held  concentric  with  the  head  spindle  and  properly 
cleared  will  produce  excellent  results. 


Fig.   17L  —  Hollow  Mills  and  Clamp  Collar 

Fig.  171  illustrates  a  form  of  hollow  mill.  The  clamp  collar  shown 
in  the  group  is  commonly  used  for  slightly  adjusting  the  teeth  to  cut  to 
correct  diameter.     Another  good  form  of  clamp  ring  is  shown  in  Fig.  172. 

,  Taper  =  M  per  Foot 


;  Finishing  } 
(  Roughing  -* 

Ke 

?& 

% 

y.-r. 

% 

'A-2 

K 

'%! 

Ke 

% 

K 

% 

X 

D= 

.072 

.104 

.135 

.106 

.197 

.229 

.20 

.291 

.322 

.385 

.510 

.635 

.700 

L    = 

K 

M 

% 

y^. 

% 

% 

Vm 

'4, 

M 

% 

% 

% 

1 

•"•       10    ~ 

.006 

.009 

.012 

.015 

.019 

.022 

.025 

.028 

.031 

.038 

.050 

.063 

.075 

I    = 

% 

rm 

y^, 

Jfe 

Mo 

% 

% 

% 

% 

% 

Vi, 

13/ 
/l6 

O  = 

% 

% 

% 

% 

% 

% 

% 

% 

% 

1 

m 

1% 

1% 

FIG.  173 

Clamp-Collar  and  Hollow-Mill  Dimensions 

This  is  made  with  sufficient  metal  at  one  side  to  admit  the  clamping 
screw,  while  the  opposite  side  of  the  ring  is  weak  enough  to  allow  it  to 
close  properly  upon  the  mill  when  adjusted  by  tlie  screw. 


TAPEK-TrRMXd   TOOL 


183 


The  tcoth  (»f  hollow  mills  should  he  r:i<li:il  or  ahead  of  the  center. 
With  the  cutting  edge  ahead  of  the  center,  as  in  Fig.  173,  the  chips  as 
produced  are  caused  to  move  outward  away  from  the  work  and  prevented 
from  disfiguring  it.  With  the  cutting  edge  below  the  center,  rough  turn- 
ing will  result.  With  the  cutting  edge  greatly  above  the  center,  chatter- 
ing is  produced.  About  one-tenth  of  the  cutting  iliameter  is  found  a 
good  average  amount  to  cut  the  teeth  ahead  of  the  center.  When  the 
chips  produced  from  any  turning  or  boring  cut  curl  nicely,  it  is  indicative 
of  a  free  cutting  action;  but  these  diips  are  very  troublesome  on  the 
automatic  screw  machine.  In  making  hollow  mills  for  the  automatic, 
part  or  all  of  the  rake  to  the  cutting  edge  is  generally  sacrificed. 

HOLLOW-MILL    I'RoroHTIOXS 

The  table  under  the  holiow-mill  sketch  in  Fig.  173  gives  proportions 
of  mills  from  iV  to  f  diameter,  showing  the  amount  to  cut  the  teeth  ahead 
of  the  center,  the  amount  of  taper  in  the  hole,  etc. 

Besides  the  type  of  mill  shown  made  in  one  piece,  hollow  mills  are 
often  used  with  inserted  blades  of  high-speed  steel.  These  tools  are 
especially  useful  on  the  larger  sizes  of  work. 

TAI'ER-TLRNIXG    TOOL 

So  far  we  have  discussed  conditions  where  cuts  are  cylindrical  and 
where  box  tools  with  stationary  cutting  tools  and  back  rests  are  suitable. 
On  taper  work  the  cutting  tool  must  move  radially;  tlie  back  rest,  unless 
it  i)rece(les  the  cut,  must  be  so  constructed  as  to  adjust  itself  to  the 
increase  or  decrease  in  diameter. 


Tig.  17 i.  —  TiijxT-tiirniiiji  Bo.v  Tuul 

Fig.  174  illustrates  a  type  of  box  tool  for  taper  work  which  is  suitable 
when  uniform  bright-drawn  stock  is  used.  The  back  rest  consists  t)f  a 
stationary  bushing  fully  enveloping  the  bar.     The  hole  should  be  about 


184       BOX   TOOLS   AND    OTHER   EXTERNAL   CUTTING    APPLL\NCES 

0.0005  oversize  and  nicely  lapped.  The  cutting  tool  is  held  in  a  trans- 
verse sliding  nieniljer,  the  cross  movement  to  the  slide  l^eing  controlled 
by  a  taper  bar  mounted  on  the  cross  slide  of  the  screw  machine.  The 
taper  bar  is  sometimes  made  in  two  pieces  which  may  be  adjusted  in  such 
a  manner  as  to  permit  varying  angles  of  tapers  to  be  producetl.  This 
tool  allows  only  one  cut  to  be  taken  over  the  work  unless  the  support 
from  the  back  rest  is  dispensed  with. 


SOME    POINTS    IN    BACK-REST    CONSTRUCTION 

Having  now  illustrated  various  types  of  box  tools  and  their  rests, 
hollow  mills,  etc.,  a  few  words  relative  to  the  actual  making  of  certain 
box-tool  parts  may  be  of  interest. 

In  making  back  rests  of  the  quarter-bearing  type,  as  shown  by  Figs. 
160  and  161,  the  usual  custom  is  first  to  bore  out  the  solid  block  from 
0.0005  to  0.001  inch  over  the  size  that  is  to  be  turned,  and  plane  away 
the  portion  indicated  at  A,  Fig.  175.  The  hole  should  be  very  smooth 
and  cylindrical.  Low-carbon  tool  steel  is  very  good  for  the  purpose, 
providing  the  work  is  pack  hardened;  otherwise  it  is  preferable  to  use 
high-carbon  steel  and  harden  in  an  open  fire. 


Back  Kest      V_yt 


Splitting 
Emery 
,\  Wheel 


Fig.  175. 


XJZJJ 

I 

Cutting  Out  Corner  of  Back 
Rest 


After  the  back  rest  has  been  hardened  and  assembled  in  the  box-tool 
frame,  the  bearing  may  be  slightl}'  lapped  with  emer}-  by  holding  a  cylin- 
drical piece  of  brass  of  correct  diameter  in  the  screw  machine  chuck.  The 
turret  slide  being  moved  back  and  forth  will  very  quickly  cause  the  lap 
to  correct  any  slight  crookedness  due  to  the  hardening. 

"When  an  exceptionally  nice  job  is  required,  the  back  rest  may  be 
hardened  after  cutting  in,  as  at  B,  Fig.  175;  afterward,  by  using  a  slitting 
emery  wheel  the  corner  may  be  removed  entirely,  leaving  a  little  over 
the  quarter  bearing. 

It  is  found  good  practice  to  give  back  rests  a  width  equal  to  one  or 
one  and  one-half  times  the  tliameter  of  the  work  they  are  used  on.  It 
often  happens,  of  course,  that  the  positions  of  the  cutting  tools  necessi- 
tate the  employment  of  two  rests  in  one  box  tool. 


THE  T.\.\GENT  CLlTEIt 


185 


HOX-TOOL   CUTTERS 

It  may  be  stated  that  pre.sent-day  practice  favors  the  use  of  high- 
carbon  steel  for  the  radial  type  of  tools  and  higli-speed  steel  for  tangent 
cutters  on  heavy  roughing  cuts. 

Sections  reconinieniled  for  box-tool  cutters  are  as  f(illo\vs:  For  box 
tools  used  for  stock  diameters  up  to  ^%  inch,  f'V  inch  square;  up  to  ^  inch 
diameter,  7?  i^^^b  s(|uare;  up  to  \  inch  diameter,  \  inch  square;  up  to 
I  inch  diameter,  /,-  inch  square;  up  to  1  inch  diameter,  §  inch  square;  up 
to  U  inches  diameter,  h  inch  square. 


THE       TANGENT       CUTTER 

Wliilc  the  box  tool  shown  in  Figs.  100  and  101  has  been  called  the 
tangent  tool,  actually  the  cutter  should  not  l)e  exactly  tangent  to  the 
diameter  to  1)0  turned,  as  it  is  then  impossible  to  adjust  this  type  of  cutting 


■  Cutter « 


FIG.  I  78 


A  =  Full  Diameter  of  Work 

B-Half         

C  -  Amount  Cutting  Kd^e  of  Cutter  ia  below  a 

Line  Tangent  to  Uiameter  of  Work.  i.OOB"to  .008") 
D=B-C 

FIG.   176 


Section  F-G 


Giz 


nc.  179 


FIG.   177 


Box-Tool  flitter.'^ 


tool  so  as  to  cut  under  size,  although  by  withdrawing  the  tool  oversize 
work  can  be  turned.  In  order  to  be  able  to  compensate  for  slight  errors 
ami  to  insure  that  work  may  be  turned  to  fit  the  non-adjustable  back 


186       BOX   TOOLS  AND   OTHER   EXTERNAL  CUTTING   APPLIANCES 

rest,  it  is  the  practice  to  plane  the  cutter  block  so  that  the  cutting  edge 
of  the  tool  is  about  0.002  inch  to  0.003  inch  below  a  line  tangent  to  the 
diameter  actually  to  be  turned,  as  at  C,  Fig.  176. 

The  effect  of  in-and-out  adjustment  of  the  cutter  is  clearly  shown  by 
Fig.  177. 

AN    OPERATING    SUGGESTION 

In  order  to  facilitate  the  '^starting  on"  of  the  box  tool,  it  is  well  to 
have  the  end  of  the  work  beveled,  as  in  Fig.  178.  The  forming  tool  in 
finishing  the  head  of  the  work  simultaneously  bevels  a  portion  of  the  bar 
at  E^  which,  when  a  new  piece  of  work  is  being  produced,  becomes  E^. 
The  first  cut  of  the  box  tool  is  thus  made  light  and  does  not  become  heavy 
until  after  the  support  of  the  back  rest  has  been  secured. 

Fig.  179  illustrates  an  end-pointing  tool  used  on  the  type  of  box  tool 
just  referred  to.  The  form  is  planed  in  the  end  of  the  cutter  as  indicated, 
thus  permitting  frequent  grinding  without  altering  the  form.  Sometimes 
for  pointing  work  a  special  pointing  box  tool  is  employed,  carrying  merely 
a  back  rest  and  a  pointing  cvitter;  frequenth^  a  regular  roughing-box  tool 
is  utilized  and  the  pointing  cutter  held  in  the  hollow  shank  and  prevented 
from  moving  by  a  set  screw. 


CHAPTER   XXI 1 1 
Drills,  Counterbores  and  Other  Ixterxal  Cutting  Tools 

The  (lc.sio;n  of  intei-nal  cutting  tools  is  largely  governed  by  tlie  char- 
acter of  the  material  to  be  cut,  the  depth  of  hole,  and,  in  tools  for  finish- 
ing, the  amount  of  material  left  by  the  roughing  tool  for  removal. 

As  witii  external  cutting  tools  the  clearance  and  rake  of  the  cutting 
edges,  the  number  of  cutting  edges,  and  the  means  of  avoiding  accumu- 
lation of  chips  must  be  considered  in  connection  with  the  nature  of  the 
material  to  be  cut. 

STARTING    drills 

It  is  generally  advisable  before  attempting  to  drill  a  long  hole  to  use 
what  is  termed  a  starting  drill,  which  tool  is  usually  either  of  the  flat 
type,  as  shown  in  Fig.  180,  or  somewhat  similar  to  a  twist  drill,  only  having 
short  flutes  like  Fig.  181.  The  point  should  be  quite  thin  and  the  lip 
angles  more  acute  than  the  drill  that  is  to  follow,  as  in  this  event  the  outer 
diameter  of  the  drill  is  j)erniitted  to  cut  before  its  blunt  non-cutting  cen- 
ter web  comes  in  contact  with  the  work.  Fig.  182  illustrates  a  twist 
drill  entei'ing  a  piece  of  woi'k  that  has  jjreviously  been  spotted  with  a 
starting  drill,  and  the  twist  drill  will  be  found  to  I'uu  true  under  these 
conditions.  When  the  blunt  center  web  of  a  drill  is  allowed  to  come  in 
contact  with  the  work  first,  as  in  Fig.  18.'?,  the  value  of  the  starting  tlrill 
is  not  nearly  as  great  as  under  the  conditions  in  Fig.  182.  For  starting 
drills  under  \  inch  in  diameter  the  flat  starting  tool.  Fig.  180,  is  very  satis- 
factory, while  for  larger  work,  except  brass  and  similar  materials,  the  type 
illustrated  by  Fig.  181  is  more  commonly  used. 

SPOTTING    AND    FACING    TOOLS 

On  long,  slender  work  made  of  smooth  stock  dose  to  size  and  which 
projects  some  distance  from  the  head  spindle  it  is  generally  found  neces- 
sary to  support  the  end  of  the  woik  close  to  the  point  being  spotted, 
and  in  such  cases  the  starting  or  spotting  ilrill  is  held  in  a  holder  which 
is  also  suitable  for  guiding  the  outer  enil  of  the  work.  Fig.  184  illustrates 
a  tool  of  this  type. 

In  some  cases  combination  spotting  and  end-facing  tools  like  Fig. 
185  arc  used.  This  tyjje  of  tool  is  veiy  satisfactory  on  bra.>^s  work,  etc., 
but  on  harder  materials,  such  as  steel,  which  is  more  destructive  to  the 

187 


188     DRILLS,  COUNTERBORES  AND  OTHER  INTERNAL  CUTTING  TOOLS 


cutting  edges  and  thus  makes  frequent  regrinding  necessaiy,  a  tool  holder 
havmg  separate  starting  and  facing  cutters,  as  shown  in  Fig.  186,  is  pref- 
erable, as  the  independent  adjustments  allow  frequent  sharpening  to  be 
more  economically  accomplished. 


FIG.  189 


Clearance  on 
Periphery  of  Drills 


Clearance  on  Periphery 
of  Couuterbores 


Spotting  Tools  and  Drills 


FIG. 191 


TWIST   AND    STRAIGHT   FLUTE    DRILLS 

In  drilling  cylindrical  holes  standard  commercial  tools  are  preferred 
owing  to  the  convenience  of  replacement  when  they  become  worn  out  or 
broken.  Ordinary  twist  drills  are  very  satisfactory  in  steel  and  cast 
iron,  although  in  very  deep  holes  the  chips  are  sometimes  difficult  to  get 
rid  of,  and  clogging  up  of  the  flutes  and  occasional  breakage  will  then 
occur  unless  frequent  withdrawing  of  the  drill  is  resorted  to.  On  brass 
and  all  free  cutting  stock  the  rake  given  to  the  cutting  edges  of  twist 
drills  generally  causes  excessive  curl  to  the  chips  and  thus  makes  the 
automatic  removal  of  the  chips  from  the  hole  difficult.  On  automatic 
screw  machines  oftentimes  a  long  curled  chip  is  very  objectionable  as 
some   machine   functions  may   be  interfered   with.     For  these  reasons, 


BACK    AM)    LAM)   ("MCARANCES  ISO 

when  twist  diilLs  arc  used  in  brass,  it  is  gooil  practice  to  reduce  this  rake 
by  grinding  in  the  Ups  at  tlie  front  end,  as  in  Fig.  1X7. 

A  two-lip,  straight-fluted  drill  commonly  known  as  a  "  I'arnier"  drill 
is  generally  superior  to  the  twist  drill  in  cases  where  tlie  curling  of  the  chips 
is  troublesome,  and  in  shops  where  bra.ss  work  predominates,  this  drill 
is  used  nmch  more  connnonly  than  the  twist  drill. 

SEKHATEl),    FLUTKI)    AM)    STKl'I'KI)    LII'.S 

The  cutting  edges  of  drills  are  sometimes  serrated  as  indicated  in 
Fig.  1S8  to  produce  narrower  ciiips  than  would  otherwise  result  and 
facilitate  their  easy  removal.  A  similar  effect  is  produced  by  fluting  the 
ihill,  as  shown  by  Fig.  ISO.  Still  another  method  of  producing  narrow 
chips  is  to  step  the  end  of  the  drill.  It  may  be  of  interest  to  mention 
that  this  latter  scheme  is  very  connnonly  u.sed  in  the  one-lip  drills  for 
drilling  long  holes  in  gun  barrels,  spindles,  etc.  Fig.  100  will  give  an  idea 
of  this  type  of  tool.  When  such  a  drill  is  carefully  guided  and  advanced 
at  a  low  rate  of  feed  it  is  possible  to  drill  a  distance  of  30  or  40  inches 
with  not  more  than  0.010  inch  curvature  in  the  length  of  the  hole.  There 
is  no  center  web  to  prevent  free  cutting  as  in  the  two-lip  twist  drill,  and 
oil  is  forced  under  pressure  to  keep  the  cutting  cool  and  conduct  away 
chips.  The  use  of  oil  in  this  manner  is  found  very  effective  with  all 
classes  of  internal  cutting  tools,  except  when  operating  in  cast  iron.  It 
makes  possible  the  runnmg  of  work  at  a  high  peripheral  speed  without 
excessive  heat,  results  in  rapid  cutting  and  insures  long  life  to  the  cutting 
edges  of  the  tool. 

The  center  edge  of  all  twist-  and  straight-flute  drills  should  be  thinned 
down  at  the  cutting  point,  as  the  drill  will  then  cut  more  freely  and  less 
power  be  re<[uired  for  the  work. 

BACK    AM)    LAM)    CLEARAN'CES 

Drills  .should  have  some  back  clearance,  from  0.007  to  O.Olo  inch  per 
foot  being  common  practice.  The  land  back  of  the  cutting  edge  should 
be  quite  narrow  as  little  land  is  required  to  support  the  drill  and  prevent 
chattering,  while  an  excessive  width  increases  friction  and  heat,  resulting 
in  the  welding  of  chips  to  the  drill  along  these  surfaces  ami  the  conse- 
quent production  of  rough  holes  of  varying  diameter.  Fig.  101  repre- 
sents the  manner  in  which  drills  and  counterbores  should  be  cleared  on 
their  peripheries. 

The  milling  cutters  used  to  flute  twist  and  other  drills  should  be  of 
such  form  as  to  produce  a  straight  cutting  etlge  on  the  drill.  If  there 
is  a  curve  to  the  cutting  edge  curved  chips  are  produced  which  are  diffi- 
cult to  bend  or  curl  and  such  chips  not  only  cause  exces.sive  heat,  but 
severe  strain  on  the  cutting  tool  and  fri'cpient  breakage  of  the  latter. 


190     DRILLS,  COUNTERBORES  AND  OTHER  INTERNAL  CUTTING  TOOLS 

The  various  steps  on  short  internal  cyUndrical  cutting  tools  should 
be  tapered  back  about  0.020  inch  per  foot,  and  the  peripheral  contact 
reduced  to  a  minimum  so  as  to  give  ample  chip  clearance  and  avoid  weld- 
ing of  chips. 

FLAT    DRILLS    AND    COUNTERBORES 

Fig.  192  illustrates  a  type  of  tool  commonly  termed  a  flat  drill,  which 
is  extensively  used  on  brass  work;  it  is  especially  recommended  for  such 
material  where  there  are  numerous  shoulders  or  forms  to  be  cut  out.  The 
tool  has  a  cylindrical  shank  which  fits  a  turret  tool  holder.  On  large 
work  it  is  customaiy  to  make  the  flat  drill  of  rectangular  stock  and  util- 
ize a  special  holder,  as  shown  in  Fig.  193. 


FIG. 196 


Flat  Drills  and  Counterbores 


FIG.  197 


Such  tools  when  held  in  the  turret,  as  in  Fig.  194,  should  be  placed 
with  the  faces  vertical  so  as  to  prevent  them  from  cutting  appreciably 
■oversize  if  the  indexing  of  the  turret,  due  to  wear,  is  not  perfect.  In  the 
event  of  the  turret  holes  after  long  usage  being  badly  out  of  line,  an 
adjustable  holder  should  be  used.  A  tool  of  this  character  is  illustrated 
in  Fig.  195. 

A  one-lip  drill  or  counterbore  with  a  heUcal  cut,  as  represented  in  Fig. 
196,  is  found  superior  in  many  cases  as  it  permits  of  grinding  the  cutting 
edge  without  changing  the  form  of  the  hole  produced. 


MArniXE   REAMERS  191 

Countcrboros  as  well  as  drills  slunilil  have  sufficient  back  and 
peripheral  clearance  but  should  nut  have  too  many  cutting  lips.  A  back 
clearance  of  about  0.020  inch  per  foot  is  satisfactor}-.  For  counteiboics 
up  to  1  inch  three  flutes  or  cutting  lips  are  ample;  moie  flutes  are  apt  to 
result  in  insufficient  chip  space. 

STEPPED    COUXTERBORE.S 

In  making  stepped  counterbores  where  chips  bother,  it  is  conducive 
to  good  results  to  provitle  only  one  cutting  edge  for  each  step  and  to 
have  successive  cutting  edges  arranged  spirally  on  adjacent  cutting  lips. 
Fig.  11)7  illustrates  a  stepped  counterbore  for  rougiiing  a  hole  that  is 
afterward  to  be  finished  by  a  taper  reamer.  The  advantage  of  this  stepped 
counterbore  lies  in  its  producing  a  hole  with  a  number  of  slight  steps 
without  an  undesirable  quantity  of  chips  to  wedge  antl  cause  trouble. 
For  brass  work  the  flutes  of  counterbores  should  generally  be  parallel 
with  the  body  of  the  tool,  while  on  steel  the  flutes  should  be  cut  so  as  to 
give  a  positive  rake  angle  of  10  to  1.5  degrees;  the  deeper  the  hole  to  be 
countcrbored  the  less  the  angle  of  the  tool.  For  steel,  and  particularly 
in  deep  holes,  internally  lubricated  counterbores  are  effective  in  keeping 
the  edges  cool  and  in  forcing  out  chips.  The  various  effects  produced 
by  counterbores  with  their  cutting  edges  ahead  or  behind  center,  tiie  value 
of  proper  rake  and  lubricants,  are  discussed  in  Chapter  XX\'1I  un  cling- 
ing of  chips  to  screw  machine  tools. 

MACHINE    REAMERS 

Machine  reamers  are  generally  used  for  finishing  holes  smoothly  and 
to  size,  and  consequently  it  is  advisable  not  to  leave  too  much  stock  for 
these  tools  to  remove.  On  steel  work  from  |  to  1  inch  in  diameter,  from 
0.004  to  O.OOS  inch  is  generally  satisfactory,  while  in  brass  from  0.00()  to 
0.012  is  a  suitable  amount.  It  is  well  to  have  the  teeth  of  all  reameis 
unevenly  spaced,  as  there  is  then  less  liability  of  chattering  than  where 
even  spacing  is  adopted. 

Cylindrical  reamers  should  only  cut  on  the  front  end  in  entering  a 
hole;  they  cut  back  of  the  front  end,  on  the  Ups,  only  when  the  material 
being  reamed  alternately  expands  and  contracts  through  undue  pressure 
or  variation  in  temperature  protluced  by  the  cutting  action.  This  latter 
is  particularly  noticeable  in  brass  tubing.  .Most  cylindrical  reaming  tools 
like  Fig.  19S  are  cleared  the  entire  length  of  their  cutting  lips  as  well  as 
having  a  back  taper  of  about  0.004  inch  per  foot.  For  reaming  steel 
where  it  is  desired  to  produce  an  accurate  smooth  hole  the  so-termed 
rose  reamer,  Fig.  199,  is  excellent.  This  tool  can  cut  only  on  the  front 
end,  and  must  be  well  lubricated  and  not  forced  so  as  to  expand  the  work. 
It   will   ream  holes  under  these  conditions  that  are  satisfactorv  to  the 


192     DRILLS,  COUNTERBORES  AND  OTHER  INTERNAL  CUTTING  TOOLS 


most  exacting.  For  this  work  a  rose  reamer  is  better  than  a  reamer  with 
peripheral  clearance,  as  its  weight  is  more  satisfactorily  supported  and 
there  is  thus  more  certainty  of  a  round  hole  being  reamed.  A  rose 
reamer,  as  intimated,  has  no  peripheral  clearance  on  the  flutes,  but  should 
be  back-tapered  about  0.00-i  inch  per  foot. 


FIG. 199 


One  Cutting  Lip  only 


-»  U.About  H2 


Two  Back  Eest  or 
Supporting  Lips 


Reamers  and  Reamer  Holder 


THE    CUTTING    EDGES 


The  cutting  edges  of  reamers  are  seldom  undercut  and  are  generally 
on  center,  although  for  brass  it  is  considered  by  many  advisable  to  mill 
the  cutting  edge  ahead  of  center  and  so  secure  a  scraping  cut.  The  flutes 
are  generally  milled  parallel  with  the  body  of  the  reamer,  but  in  many 
cases  a  spiral-fluted  reamer  has  been  the  means  of  obviating  chattering. 

The  spiral  should  be  cut  left-hand  to  prevent  drawing  in.  In  small 
work,  particularly  brass,  a  flat  reamer  like  Fig.  200  gives  good  results. 
It  is  inexpensive  to  make,  and  may  be  readily  re-sharpened  as  indicated. 

Reamers  or,  more  correcth',  boring  tools  with  three  flutes  and  with 
only  one  cvitting  edge  as  shown  by  Fig.  201  are  found  veiy  useful  for 
producing  straight,  deep  holes. 


REAMER    HOLDERS 

Usually  reamers  for  cylindrical  holes  (and  sometimes  finish  counter- 
boring  tools)  are  carried  in  holders  permitting  of  a  floating  action  of  the 
reamer.  When  a  reamer  is  held  rigidly  in  the  turret  hole  there  is  almost 
a  certainty  of  its  cutting  an  oversize  and  tapering  hole  clue  to  the  im- 
practicability of  retaining  the  turret  hole  in  perfect  alinement  with  the 
work  spindle.  There  are  a  variety  of  floating  reamer  holders  used.  A 
simple  form  is  illustrated  in  Fig.  202.  With  a  reamer  held  in  a  suitable 
floating  holder  and  providing  the  end  of  the  hole  that  is  to  be   reamed 


RECESSING   TOOLS  193 

has  been  Ijorcd  out  so  us  to  run  true,  and  from  0.003  to  O.Olo  untlorsize, 
there  sliould  be  produced  a  lioh'  true  to  size  and  concentric. 

NIMHKK    OF    FLUTES    I.\    KEAMEKS 

The  number  of  Ikites  cut  in  (ordinary  reamers  should  \)v  as  indicated 
by  the  following  table: 


Hand. 

Fluted  Chucking. 

i  to    /j  diameter    4  flutes. 

i 

to    ^~s  diameter    G  flute.s. 

\  to    ',  J  diameter    6  flutes. 

i 

to  IJ    diameter    8  flutes. 

i   to  1}    diameter    8  flute.s. 

lA 

to  IJJ  diameter  10  flutes. 

1/j  to  Ijl  diameter  10  flutes. 

If 

to  2, "a  diameter  12  flutes. 

If    to  'ij",  diameter  12  flutes. 

2i 

to  2 J    diameter  14  flutes. 

2 J    to  2 J    diameter  14  flute.5. 

2,*« 

to  3      diameter  10  flutes. 

2JI  to  3      diameter  16  flutes. 

T.\PER    RE.\MERS 

Taper  or  formed  reamers  should  be  provided  with  clearance  the  entire 
length  of  their  cutting  lips.  The  lips  or  huuls  instead  of  being  continu- 
ous are  in  the  case  of  long  reamers  usually  serrated  by  means  of  a  narrow 
left-hand  spiral  groove,  and  this  breaks  up  the  chip  into  a  number  of 
curled  strips  instead  of  producing  a  single  wide  one.  The  flutes  in  taper 
reamers  arc  sometimes  milled  left-hand  so  as  to  prevent  pulling  in,  and 
sometimes  right-hand  to  assist  in  cutting.  On  slight  tapers  any  tentlency 
to  draw  in  must  be  obviated  owing  to  the  risk  of  breaking  the  tool,  while 
on  steep  tapers  which  resist  the  feeding  in  of  a  tool  an  opposite  effect 
is  desired. 

In  practice,  therefore,  it  is  found  satisfactoiy  from  the  cutting  point 
of  view,  to  make  the  flutes  left-hand  in  reamers  producing  holes  tapering 
from  0  to  about  1^  inch  per  foot.  From  U  to  21^  inches  taper  per  foot 
the  flutes  may  be  straight,  while  on  tapers  greater  than  tiiis  a  right-hand 
flute  is  satisfactoiy.  This  latter  gives  a  positive  rake  to  the  cutting  edge, 
and  less  end  pressure  is  rccjuired  to  force  the  tool  to  the  cut  than  with 
straight  or  left-hanil  (lutes. 

The  cost  of  nuiking  tools  with  right-  or  left-hand  llutes  is  somewhat 
greater  than  for  straight  flutes,  and  grintling  is  not  so  readily  accom- 
plished with  ordinaiy  equipment,  hence  straight-flute  taper  reamers 
are  more  commonly  u.sed. 

RECESSING    TOOLS 

Recessing  tools  constitute  still  another  class  of  internal  cutting  appli- 
ances used  on  screw  machine  work  for  forming  grooves  and  chambers  in 
pieces  after  they  have  been  drilled  or  bored  out  as  required.     There  are 


194     DRILLS,  COUNTERBORES  AND  OTHER  INTERNAL  CUTTING  TOOLS 

many  types  of  recessing  appliances,  and  one  is  illustrated  in  Fig.  203.  The 
body  A  has  a  shank  fitting  the  turret  hole,  and  carries  a  stud  upon  which 
is  pivoted  the  tool  holder  B  in  which  is  inserted  the  cutting  tool.  This 
swinging  member  B  is  held  normally  in  central  position  by  loop  spring 
C.  In  operation,  after  the  tool  has  entered  the  hole  in  the  work  to  the 
required  point  the  cross  slide  advances,  and,  acting  upon  adjusting  screw 


Make  to  suit  Work 


Fig.  203.  —  Recessing  Tool 

D,  presses  the  holder  B  toward  the  rear  and  causes  the  tool  to  cut  the 
internal  channel  in  the  work.  If  a  chamber  or  recess  of  some  length  is 
to  be  formed,  the  turret  slide  then  advances  and  the  tool  takes  a  boring 
cut  along  the  side  of  the  hole.  Upon  completing  its  work,  the  tool  is 
relieved  by  the  cross  slide  receding,  and  is  returned  to  central  position 
by  spring  C  which  presses  the  pivoted  tool  holder  B  forward  until  a  stop 
plug  E  contacts  with  stop  pin  F  in  the  shank.  The  turret  then  withdraws 
the  tool  from  the  work. 


CIIAI'TIIK    XXI\' 

SCUKW    Ma<   IIINK    TaI'S     AM)     DiES 

Taps  and  dies  form  ii  vcr\-  iiitcrosting  topic  I'nr  discussion  anionji  tool- 
makers,  and  as  the  conditions  under  which  they  are  used  have  quite  a 
bearinji  on  their  correct  desi<>:n.  it  is  the  case  that  iileas  as  to  their  specific 
dcsiiiu  are  greatly  at  variance.  Possibly  the  selection  of  the  steel  used 
and  the  manner  in  which  the  hardening  is  accomplished  have  a  more 
important  bearing  on  results  than  in  the  case  of  any  other  class  of  cut- 
ting tools.  This  chapter  is  not  intended  to  cover  this  phase  of  the 
subject,  but  it  nuiy  be  opportune  to  state  that  in  our  experience  it  has 
been  found  best  from  an  economical  standpoint  to  temper  a  tap  quite  a 
little  lower  than  a  die.  E.xceedingly  hard,  brittle  taps  aie  liable  to  fre- 
quent breakage  on  account  of  their  relatively  weak  cross-section  and 
small  chip  space  as  compared  with  a  die. 

Keeping  taps  sharp  is  more  economical  than  continually  making  new 
ones  to  replace  those  breaking  on  account  of  being  unduly  hard.  A  die, 
however,  may  be  so  designeil  as  to  have  ample  metal  for  strength  and 
much  more  chip  room  than  the  tap,  and  consecjuently  breakage  from  this 
cause  is  not  so  liabh*  to  occur  as  with  the  tap.  Furthermore,  re-grinding 
of  a  die  is  considered  more  difHcult  than  re-grintling  a  tap,  and  therefore 
the  die  is  generally  left  harder  than  the  tap.  The  speed  of  work  while 
external  threading  operations  are  performed  may  l)e  higher  than  for  in- 
ternal threading  on  account  of  the  foregoing  rea.sons  and  also  becau.se  of 
gi-eater  facility  for  properly  lul)ricating.  Tables  of  speeds  for  dies  and 
suggestions  on  lubiicating  are  given  in  ('hai)teis  XX  and  XX\T1. 

TYPES    OF    DIES    AND    TAPS 

Fig.  204  represents  what  is  commonly  known  as  a  spring  screw-thread- 
ing die,  with  its  clamping  or  size  adjusting  ring,  and  Fig.  205  a  button 
die.  Both  of  these  tools  are  used  extc^nsively  in  the  automatic  screw 
machine.  On  large  work  dies  with  inserted  chasers,  one  form  of  which 
is  shown  in  Fig.  2(K).  are  found  very  satisfactory.  \'arious  types  of  open- 
ing dies  are  also  being  successfully  u.sed  on  different  cla.sses  of  work. 

Taps  are  generally  made  solitl,  although  there  is  doubtless  economy 
in  the  inserted  blade  type  of  tap  when  of  large  dimensions.  Collapsing 
taps  are  also  made  for  some  lines  of  work. 

195 


196 


SCREW    MACHINE   TAPS    AND   DIES 


Fic.  204.  —  Spring-Screw  Threading  Dies 


Fig.  20.").  —  Button  Dies 


til 

Fig.  206.  —  P.  A:  ^Y.  Inserted  Chaser  Die 


SPRING    DIE.S 

Owing  to  the  movable  parts  which  may  affect  perfect  ahnement  be- 
tween the  turret  hole  and  the  head  spindle  of  turret  machines,  it  is  found 
impracticable  to  hold  dies  or  taps,  even  if  perfectly  true  and  concentric, 
directly  in  a  turret  hole  or  in  a  rigid  non-adjusting  tool  holder.  Ordinary- 
commercial  spring  screw-threading  dies,  even  when  mounted  in  holders 
permitting  of  side  play,  are  apt  to  produce  better  results  if  made  with 
three  cutting  edges,  as  in  Fig.  207,  than  if  provided  wath  four  or  more 
cutting  edges.     With  the  latter,  the  result  due  to  changes  in  hardening 


SPRING   DIES 


197 


or  imperfect  workmanship  is  apt  to  be  that  only  two  diametrically  oppo- 
site teeth  are  sinuiltaneously  cuttinp;,  as  shown  in  Fis;.  20S.  This  causes 
the  die  to  vibrate  and  produce  a  rough  thread,  with  chatter  marks,  ^^■ith 
commercial  dies  having  three  cutting  edges  and  providing  that  they  are 
mounted  in  a  free  holder  these  troubles  are  greatly  reduced.     On  one 


FIG.  207 


FIG. 208 


FIG.  210 


FIG. 211 


FIG.  209 


Dip 

111   Lt 

to  Ik 

aa  Pot 
>re 

AAA/V^ 

Ay^ 

\\ 

"\ 

FIG.  21. 


FIG.  213 


FIG. 214 


Spring  Dies 


occa.sion,  in  the  designing  and  tooling  of  70  turret  machines  for  a  foreign 
order,  about  half  of  which  machines  were  automatics,  it  was  decided  to 
make  all  of  the  .spring  screw-threading  dies  with  three  teeth  only.  The 
diameters  of  work  to  be  threailed  were  from  3  millimeters  (approximately 
I  inch)  to  32  millimeters  (appro.ximately  l\  inches)  and  the  threads  per 
inch,  with  the  excejition  of  the  large  sizes,  somewhat  less  in  number  than 
United  States  standartl.  The  parts  to  be  machined  were  of  low-carbon 
tool  steel,  cold  drawn   machineiy  steel,  brass,   and  also  some  copper. 


198  SCREW   MACHINE   TAPS   AND   DIES 

Excellent  results  were  obtained  in  hardening,  and  onh'  three  dies  were 
cracked  or  ruined  by  the  fire.  There  was  not  a  single  die  ivhich  gave  any 
trouble  whatsoever  when  setting  up  and  testing  the  equipment.  This 
record  would  have  been  impossible  with  four-tooth  dies. 

TAPPING    OUT    THE    DIE 

It  is  good  practice  in  making  spring  screw  dies  to  either  hob  out  the 
thread  with  a  hob  tap  0.005  to  0.015  inch  oversize,  according  to  size, 
and  in  use  to  spring  the  prongs  to  proper  cutting  size  by  a  clamping  ring 
as  shown  in  Fig.  204,  or  to  tap  the  die  out  from  the  rear  with  a  hob  tap 
tapering  from  ^^  inch  to  \  inch  per  foot,  leaving  the  front  end  about  0.002 
inch  over  cutting  size,  and  in  this  case  also  to  use  a  clamping  ring,  Fig. 
204.  Both  of  these  schemes  are  for  the  purpose  of  obtaining  back  clear- 
ance and  are  effective.  Theoretically,  the  use  of  the  taper  hob  is  the  best, 
and  is  to  be  preferred  especially  when  work  is  to  be  cut  with  threads 
of  included  angle  less  than  40  degrees,  as  the  shape  of  thread  produced  by 
clamping  the  prongs  of  the  die  to  a  size  below  that  at  which  it  is  hobbed 
may  then  be  affected  enough  to  be  decidedly  unsatisfactory.  Fig.  209 
illustrates  this  bad  feature. 

Fig.  210  illustrates  the  die  with  the  taper  somewhat  exaggerated,  as 
made  with  a  taper  hob  and  the  general  internal  form  of  a  very  satisfactory 
spring  screw-threading  die. 

HARDENING 

In  hardening  a  die  it  frequently  happens  that  curves  to  the  lips  are 
produced  as  in  Fig.  211.  When  clamping  the  prongs  of  an  oversized 
hobbed  die  (with  such  curvature)  down  to  size,  this  will  still  result  in  a 
bell  mouth  die.  ,  With  a  die  hobbed  out  with  a  tap  of  sufficent  back  taper, 
as  in  Fig.  210,  the  curve,  if  it  exists,  will  not  result  in  a  bell  mouth;  the 
clearance  angle  being  more  pronounced  than  with  an  oversize  tapped 
die,  neutralizes  the  curvature.  The  internal  form  shown  by  full  lines  in 
Fig.  212  is  bad,  as  the  thickness  of  metal  varies  so  that  in  hardening  trouble 
will  result.  In  Fig.  210,  and  as  shown  by  dotted  lines  in  Fig.  212,  is  a 
more  satisfactory  internal  form. 

Probably  the  best  practice  in  hardening  is  to  dip  the  prongs  into  the 
lead  pot  not  further  than  dotted  lines  W-X,  Fig.  213,  in  which  case  less 
trouble  will  result,  and  the  heat  will  still  be  sufficient  to  cause  the  remain- 
ing portion  of  the  prongs  to  be  sufficiently  hard  when  chilled,  to  prevent 
welding  of  chips,  etc. 

In  case  the  hardening  effect  extends  back  into  the  curve  as  at  Y-Z, 
side-twisting  of  the  prongs  is  almost  a  certainty,  and  the  cutting  edge  of 
the  die  in  this  event  will  not  be  in  contact  with  the  work,  but  a  portion 
back  of  the  cutting  edge  will  be  dragging  on  the  work  which  will  cause  a 
ragged  thread  and  oftentimes  break  off  the  piece  being  threaded. 


crmxr;  KDf.Es  199 

In  spite  of  faro  tlicrc  is  imicli  risk  in  the  length  of  the  prongs  being  at 
vuriunc'c  after  liar(U'nin<r.  and  it  is  conducive  to  good  results  to  leave  a 
tie  to  the  prongs  as  slunvn  in  Fig.  214.  This  tie  can  be  removed  in  two 
or  three  minutes  by  the  use  of  a  .slitting  ernen^  wheel. 

With  a  three-prong  die  it  is  possil)l('  to  jjrovide  lips  of  generous  cro.ss 
section,  giving  ligidity.  The  un(lesiral)le  fiiction  due  to  too  much  thread 
in  contact  with  the  work  is  overcome  by  milling  out  as  in  Fig.  207,  to  suit 
the  material  being  threaded. 

CUTTING    EDGES 

The  cutting  edge  of  a  spring  screw  die  is  generally  radial  for  bra.^s, 
and  it  is  permissil)le  for  the  edge  to  point  a  trifle  below  center,  particularly 
when  there  is  any  possibility  (owing  to  the  ease  of  cutting)  of  there  being 
a  strong  chip  j)roduced  which  may  cause  a  "hogging  in"  action.  On 
steel  or  nuiterial  not  free  cutting,  and  which  opposes  the  cutting  action, 
it  is  desirable  to  have  a  positive  rake  to  the  cutting  edge  so  as  to  make 
the  cutting  action  easier,  hence  the  cutting  edge  is  generally  above  cen- 
ter. The  amount  is  oidy  limited  by  the  chip  curling  so  as  to  be  objec- 
tionable on  account  of  clogging,  or  by  the  rake  being  so  much  as  to  cause 
too  free  cutting,  and  consecpiently  the  production  of  a  big.  strong  chip 
and  the  ""  hogging  in  "  action  which  in  this  event,  owing  to  the  cutting  edge 
being  above  center,  produces  very  bad  results. 

It  should  be  observed  that  where  large  diameters  of  brass  are  to  be 
threaded  and  where  the  die  is  .so  ligid  that  no  springing  action  can  take 
place,  the  radial-cutting  edge  is  not  as  desirable  as  where  there  is  posi- 
tive rake  to  the  edge. 

Chattering,  etc.,  on  large  work  is  generally  due  to  weakness  of  tool 
or  tool  holder,  and  increased  rigidity  in  these  oftentimes  makes  po.ssible 
an  increase  of  clearance  and  particularly  an  increased  positive  lake 
to  the  cutting  lip  angles  of  all  tools,  with  the  residt  of  better  cutting 
action. 

It  is  desirable  in  spring  screw  dies  to  make  the  outside  true  with  the 
axis  of  the  thread  and  cutting  edges,  and  con.sequently  it  is  found  desir- 
able to  grind  the  outside  diameter  from  the  thread.  Tiiis  is  of  particular 
value  in  connection  with  the  outside  clamping  or  sizing  ring,  as  it  assists 
in  a<ljusting  the  .several  prongs  of  the  the  ecjually,  as  well  as  nuiking  it 
unnecessary-  to  provide  undue  freedom  in  the  die-holding  device. 

On  large  work,  where  in.serted  cha.ser  dies  may  be  utilized,  it  is  evi- 
dent that  more  than  three  cutting  edges  can  be  used  with  very  little  of 
the  difficulty  common  to  the  spring  screw  die.  as  distortion  due  to  hard- 
ening is  less,  and  if  it  exists  at  all.  it  can  be  compensat(Ml  for  if  necessary. 
Furthermore,  the  desirable  side  clearance  to  each  cha.ser  may  be  readily 
given  to  this  type.     Where  more  than  three  teeth  are  found  desirable 


200  SCREW   MACHINE   TAPS   AND    DIES 

it  is  always  better  to  have  an  odd  than  an  even  number  of  teeth,  as  the 
possibiHty  of  only  two  teeth  cutting  is  then  avoided. 

MAKING    INSERTED    CHASERS 

With  inserted  chaser  "  opening  dies "  it  is  becoming  quite  common 
practice  to  mill  the  threads  of  the  chasers  with  a  milling  cutter,  thus  giving 
straight  and  ample  clearance,  instead  of  bobbing  with  a  master  tap, 
which  latter  gives  very  little  clearance  unless  greatly  oversize. 

A  feature  emphasized  by  those  milling  chasers,  instead  of  bobbing, 
is  that  when  dies  or  chasers  are  cut  by  a  master  tap  there  are  three  inher- 
ent errors  which  if  accumulative  may  be  sufficient  to  make  it  impossible 
to  obtain  perfect  pitches.  There  is  first  the  error  of  the  lead  screw  in 
the  lathe  used  in  cutting  the  master  hob;  second,  the  error  in  the  hob  due 
to  hardening;  third,  the  error  in  the  die  or  chasers  due  to  hardening.  If 
these  three  errors  act  cumulatively  the  result  is  that  an  inaccurate  die 
is  produced.  By  milling  the  chaser  the  first  two  errors  may  be  eliminated, 
leaving  only  the  error  caused  by  hardening  the  chaser,  and  this  last  error 
may  be  kept  small  by  hardening  only  the  cutting  edge,  the  unhardened 
material  at  the  rear  having  an  important  effect  in  preventing  distortion. 

It  is  furthermore  advanced  by  some  that  in  milling  the  thread  of  a 
chaser  the  metal  is  not  compressed  as  it  is  with  a  tap;  that  with  a  tap 
the  metal  is  not  really  cleanly  cut,  but  is,  so  to  speak,  more  or  less  pushed 
off  as  the  tap  has  no  clearance  and  the  resulting  surface  is  left  in  a  state 
of  strain  which  relieves  itself  when  hardening,  thus  increasing  the  dis- 
tortion both  in  form  and  in  pitch. 

BUTTON    DIES 

The  shape  of  the  round  button  die  gives  it  an  advantage  over  the  spring 
screw  die  in  hardening,  and  this  tj^pe  of  die  is  in  considerable  favor  with 
many  on  small  work.  It  is  not  considered  as  convenient  to  re-sharpen 
correctly  as  the  spring  screw  die,  but  the  low  original  cost  of  button  dies 
permits  them  to  be  discarded  when  dull.  Chips  on  coarse  pitches  are 
not  so  easily  gotten  rid  of  with  the  button  die  as  with  other  types.  It 
has,  however,  when  correctly  made,  some  very  good  features,  and  when 
fully  understood  and  made  in  proper  manner  it  is  veiy  satisfactory  for 
screws  ^^^  inch  diameter  and  under.  Owing  to  the  rigidity  of  the  button 
die  the  cutting  edge  of  the  tooth  may  always  be  ahead  of  the  center  for 
brass,  as  well  as  for  steel,  and  good  results  follow. 

This  type  of  die  should  be  made  substantially  as  in  Fig.  215,  and  in- 
stead of  bobbing  with  an  oversize  hob,  an  undersize  hob  is  superior,  the 
die  being  expanded  to  proper  cutting  size.  The  reason  for  this  is  that, 
with  the  cutting  edge  of  the  teeth  ahead  of  center  and  providing  an  over- 
size hob  be  used,  the  relation  of  the  cutting  edge  to  the  work  would  be  as 


BU'lTON    DIES 


201 


shown  ill  Fi<i.  2I(i.  when  rlosinfj  down  tho  die  which,  wh.cn  exiigfroratcd 
as  shown,  (Miiphasizes  the  bad  cutting  action  which  exists  under  normal 
conditions  to  an  objectionabh'  extent.  When  the  die  is  expanded,  as  shown 
by  Fig.  217,  the  clearance  of  the  threaded  portion  of  the  die  is  in  the  cen- 
ter, where  it  is  tlesiiable  tliat  it  should  be,  and  the  cutting  action  is  excel- 
lent. When  reversing  the  work  for  the  removal  of  the  die  there  is  no  danger 
of  the  wedging  in  of  chips. 


FIG. 217 


F 

J 

~  ;JV\><>vV^V- 

K^ 

-o.-.-.^.-.v- 



^.y//////- 

1 

FIG.  21S 


Button  Dies 


This  type  of  die,  on  account  of  the  chance  it  affords  for  what  would 
ordinarily  be  consiilered  an  excessive  rake  without  springing,  is  found 
very  sati.sfactoiy  for  cutting  copper. 

In  the  button  die,  as  shown  in  Fig.  215  and  Fig.  21S,  it  should  be 
noted  that  the  expantling  wedge  is  a  taper  pin  which  acts  as  a  tie  and 


202 


SCREW  MACHINE   TAPS  AND   DIES 


prevents  a  twist  to  the  tlic  which  might  occur  from  hardening  if  a  wedge 
were  used  as  in  Fig.  216.  The  Une  a,  Fig.  215,  representing  the  cutting 
edge  of  the  die,  may  be  pointed  on  center  or  above,  as  desired,  and  then 
the  center  of  hole  h  is  located  on  line  c  so  that  the  edge  of  the  hole  is  tan- 
gent to  the  line  a. 

APPLICATION    OF    DIE    TO    WORK 

Most  dies  are  chamfered,  so  as  to  cut  smoothly  and  to  assist  in  start- 
ing on  to  the  work,  as  in  Fig.  218,  but  it  sometimes  is  necessary  to  cut 
very  closely  to  a  shoulder  with  one  die  only,  and  in  this  event  there  can 


FIG.  219 


Forming  Tool 


FIG.  220 
Threading  Work 


be  but  little  chamfer.  It  will  be  of  assistance  in  starting  the  die  under 
these  conditions,  when  work  permits,  to  bevel  the  end  of  the  work  as  indi- 
cated in  Fig.  219,  prior  to  running  the  die  on,  and  afterward  remove  the 
bevel  at  a,  if  objectionable. 

It  sometimes  happens  that  very  short  threads  have  to  be  produced, 
as  shown  at  .4,  Fig.  220.  An  effective  method  of  producing  such  work 
is  to  first  cut  a  long  thread  and  afterward  face   off  the   extra  portion 


LENCIII    AM)    M  .\II{i;i{    OF    LANDS  203 

betwoon  nock  />'  ami  the  end  of  tlu^  j)i(  co.  The  nicking  at  B,  provi<Mis  to 
cuttinj;  the  tliroad,  is  necessary  to  prevent  a  bur,  wliidi  woulil  otherwise 
be  produced  by  the  facing  tool. 

IXTERXAL   THREADIXG 

Tlius  far  this  cliapter  has  been  confined  to  the  external  threading  of 
work;  it  should  be  remembered  that  man}'  of  tiie  conditions  are  conunon 
to  internal  tlireading  operations  also. 

Taps  have  their  cutting  etlges  cut  radially  in  most  cases,  though  on 
bra.ss  it  is  desirable  to  cut  below  center,  thus  breaking  up  the  chip  for  its 
more  ea.sy  removal.  A  free  curling  chip  is  undesiral)le  when  tapping, 
unless  the  stock  is  of  such  a  nature  that  tearing  of  work  will  result  in 
case  the  cutting  edge  is  not  such  as  to  produce  such  a  chip.  Copper  is 
a  material  of  this  nature,  and  a  tap  made  like  Fig.  221  with  a  big  rake 
to  its  cutting  edge  works  out  nicely.  On  copper  and  similarly  acting 
material,  cutting  out  every  other  tooth,  as  is  done  on  the  Kchols  patent 
taj)  made  by  the  Pratt  &  Whitney  Company,  is  found  an  efficient  means 
of  producing  clean  threads.  Fig.  222  illustrates  this  tap  and  also  shows 
it  entered  in  a  piece  of  work;  Fig.  223  represents  an  ordinary  tap. 

In  the  former  (which  is  always  made  with  an  odd  number  of  flutes), 
each  alternate  tooth  is  omitted,  the  arrangement  being  so  carrietl  out 
that  each  of  the  cutting  teeth  is  followed  by  a  space  and  each  space  by 
a  tooth.  This  arrangement  gives  a  freedom  of  action  to  each  cutting 
tooth  not  obtainable  with  the  ordinary  form  of  tap.  In  tapping  holes 
with  ordinary  taps  in  copper  and  similar  material  the  tendency  is  to  tear 
the  threads,  owing  to  the  wedging  action  of  the  cutting  teeth,  and  the 
slight  resistance  offered  by  the  metal  to  the  pressure  of  the  continuous 
row  of  cutting  edges.  The  chips  are  carried  forwartl  in  a  mass  in  front 
of  the  cutting  teeth,  and  unless  the  tap  is  fr(>(|uently  reversed,  thus  break- 
ing up  the  mass  of  chips,  the  thread  will  either  be  mutilated  or  the  tap 
broken. 

It  will  be  seen  upon  examination  of  Fig.  222  that  only  one  side  of  the 
thread  that  is  being  formed  with  the  tap  there  shown  is  operated  upon 
at  once.  It  is  thus  relieved  of  one-half  the  pressure  and  wholly  of  the 
wedging  action,  and  because  of  the  ab.sencc  of  the  next  adjacent  threads, 
a  slightly  lateral  movement  of  the  thread  being  formed  is  possii)le,  owing 
to  the  mobility  of  the  metal.  It  is  probable  that  under  similar  comli- 
tions  the  removal  of  alternate  teeth  in  a  die  would  be  of  value. 

LENGTH    AND    XIMHKK    OI'    LAXHS 

The  number  of  teeth  in  regular  taps  and  wi<lth  of  land  should  be 
regulated  by  the  diameter  and  j)itch  of  work  as  well  as  the  nature  of  the 
material  being  cut.     On  "sticky"   material  both  dies  and  taps  should 


204 


SCREW   MACHINE   TAPS   AND   DIES 


have  relatively  short  land.     On  fine  threads,  where  a  drunken  thread  is 
to  be  insured  against,  more  teeth  are  required  than  on  a  coarser  pitch  of 


FIG.    221 


FIG.  223 


FIG.  224 


Taps 


FIG.  225 


the  same  diameter.     A  good  average  number  of  teeth  on  taps  for  United 
States  standard  threads  is  given  in  the  following  schedule.     Too  few  teeth 


Outside  Diameter. 

No.  of  Flutes. 

Width  of  Land. 

A 

4 

A 

\ 

4 

tV 

A 

4 

.\ 

1 

4 

A 

tV 

4 

6T 

\ 

4 

i 

1 

4 

A 

1 

4 

tV 

i 

4 

3'^ 

1 

4 

1 

li 

4 

5 

T6 

and  too  short  land  afford  very  little  support  and  may  cause  chattering; 
too  much  land  in  contact  causes  heat  due  to  excessive  friction  and  weld- 
ing of  chips,  torn  threads,  etc. 


SPRING   DIE  SIZES 


20.-, 


TAP    HKLIKF 

Taps  for  use  in  tlu'  screw  machine  should  permit  reversing  of  tlie 
work  without  any  chance  of  cliips  wedding  at  this  point,  and  conse- 
(juently  are  not  cleared  the  same  as  hand  taps  which  go  entirely  through 
the  work  and  arc  thus  removed  without  reversal. 

Fig.  1224  illustrates  the  way  to  relieve  the  top  and  sides  of  the  teeth 
of  screw  machine  taps.  A  tap  for  long  cylindrical  threatling  should  in 
addition  be  slightly  tapering  toward  the  back  so  as  to  free  it.self.  This 
taper  should  l)e  about  0.020  to  0.030  inch  per  foot,  although  conditions 
may  make  it  desirable  to  vary  this  somewhat. 

Where  a  tap  is  used  on  steep  triple  and  quadruple  tliieatls  it  is  cus- 
tomary to  cut  the  flute  on  a  spiral  .so  as  to  present  a  square  cutting  face 
like  Fig.  22.'),  which  is  self-explanatory. 


SIZING    WORK    FOR   THREADING 

In  boring  holes  previously  to  tapping  they  should  be  somewhat  larger 
than  the  theoretical  diameter  at  bottom  of  thread,  as  the  crowding  action 
of  the  tap  will  cau.se  the  metal  to  flow  .some  and  compensate  for  this. 
Where  no  allowance  is  made,  frequent  tap  breakage  is  liable  to  occur 
and  torn  threads  in  the  work  also.  On  external  work  it  is  for  the  same 
reasons  advisable  to  turn  the  work  undersize;  the  following  table  gives 
good  average  allowances  for  both  internal  and  external  work: 


Threa. 

.s  per  Inch. 

External  Work. 
Turn  Undersize. 

Internal  Work. 

Increase  over  Theoretical 

Bottom  of  Thread. 

28 

().(M)2 

0.(K)4 

24 

().()( )J 

(».(K)4.5 

22 

(».(»( )L'.) 

0.00.", 

20 

().(M)2.5 

().()0.",5 

16 

om:i 

O.OOf) 

14 

OAHY.i 

().(M)().5 

13 

O.lMKi.") 

().(M)7 

12 

().(M);{.") 

0.007 

11 

().(M».i.j 

0.007.5 

10 

(».(M)4 

().()( )S 

9 

(».(H»4 

0.0OS5 

8 

(l.(KU.l 

0.(M><) 

7 

0.(M)4.5 

0.00U5 

6 

0.00.5 

0.010 

STRING    DIE    SIZES 


It  may  be  of  value  to  include  a  table  of  suital)le  dimensions  for  spring 
screw  dies,  and  the  data  in  the  sketch,  Fig.  226,  should  prove  of  service, 


206 


SCREW  MACHINE   TAPS   AND   DIES 


particularly  for  steel.     For  brass  the  cutting  edge  is  radial,  thus  eliminat- 
ing  dimension  A.     The  width  of  land  at  bottom  of   thread   is  usually 


Taper  of  Tap  =  }^  per  ft . 


D  = 

'•16 

?5 

^16 

H 

'-ia 

*3 

■*! 

*o 

**3 

*10 

*12 

Th'ds  P.I.  = 

Oi 

4U 

32 

20 

18 

50 

40 

■a 

^'32 

==^32 

'H^ 

A    ^  Ji- 

.0J3 

.0,2 

.019 

.025 

.031 

.010 

.oil 

.oil 

.013 

.019 

.021 

L  = 

'    16 

^i2 

% 

••. 

H 

'  32 

H 

"  32 

=  13 

'Hz 

K 

D  = 

%      to      ii 

H  to  H 

%    to    1 

Th'ds  P.I.= 

Std. 

Std. 

Std. 

A   = 

D  -J-  10 

D   -h    10 

D  -^    10 

L  = 

^ 

1" 

l'^ 

O.S.Dii. 

1" 

1?3 

1% 

LeugtU 

2" 

2Uj" 

ili" 

Fig.  226.  —  Spring  Die  Dimensions 

made  about  {  0.  D.  of  cut,  the  milling  between  flutes  being  70  degrees 
for  the  flute  and  50  degrees  for  the  prong  in  the  case  of  three-flute  dies. 

SIZING    DIES    AND    TAPS 

As  most  all  dies  have  means  for  slight  adjustment,  it  is  not  necessary 
to  use  the  same  care  in  sizing  them  as  in  the  case  of  taps  which  are  gen- 
erally non-adjustable.  Dies  may  be  "chased  out"  to  fit  a  male-threaded 
plug  and  a  tap  to  suit  a  female  gsge.  In  the  event  of  having  only  a  plug 
or  a  sample  to  work  to,  the  ball-point  micrometer  is  very  convenient  in 
comparing  dian^eters  when  cutting  the  thread  on  a  tap.  In  making  taps 
to  a  drawing  or  specification,  it  is  of  assistance  to  turn  a  portion  of  the  tap 
to  the  theoretical  bottom  of  the  thread  and  then  with  properly  formed 
threading  tools,  to  use  this  part  as  a  gage  when  sizing  the  tap,  either 
copper  plating  with  blue  vitriol  and  burnishing  the  plate  with  the  thread 
tool  or  dispensing  with  the  plating  and  using  a  good  eye-glass  to  detect 
when  actual  contact  between  the  threading  tool  and  tap  blank  at  gage- 
point  takes  place. 

TESTING    THREADING    ACTION 

When  in  doubt  as  to  the  proper  cutting  action  of  a  die  or  tap  it  is 
advisable  to  carefully  turn  or  bore  a  piece  of  work,  then  thread  the  work 
under  normal  conditions,  but  to  stop  the  work  with  the  cutting  action 
taking  place,  then  in  the  case  of  external  threading,  note  whether  all 
the  cutting  edges  are  producing  an  even  clean  chip,  or  pushing  the  thread 
off.  In  case  the  thread  in  the  die  is  smooth  and  the  cutting  edges  are 
sharp  and  have  been  properly  lubricated  and  the  work  is  poor,  the  chances 
are  that  the  angle  of  rake  or  the  clearance  is  at  fault. 


ADJUSTMKXT    TOR    J.l.N'iTH    ( •!     TllliliAI)  207 

To  examine  the  hole  tapped  out  tlie  work  must  be  carefully  sawt-il  into 
two  pieces. 

1)1 1;    HOLUEUS 

Holders  for  die  and  taps  for  the  automatic  have  much  to  do  with 
the  success  of  these  tools.  Fig.  227  shows  a  very  satisfactory  holder 
made  by  the  Pratt  &  Whitney  Company.  This  ajjpliance  was  developed 
for  u.se  in  a  screw  machine  whose  spiniUe  reverses  veiy  rapidly. 

Among  the  important  features  of  this  particular  die  holder  are  the 
following:  The  backward  movement  of  the  .sliding  die  holding  head  a, 
which,  as  usual,  occurs  in  running  off  the  die  or  tap  from  the  work,  is  never 
opposed  by  the  guide  fingers  b  b' ,  should  they  strike  against  the  ends  of 
driving  pins  c  c' ,  as  the  guide  fingers  being  pivoted  at  d  d'  swing  out  in 
this  event.  This  prevents  stripping  of  the  thread.  The  spiral  springs 
e  e'  serve  to  return  and  retain  the  guide  fingers  in  their  nonnal  parallel 
position  which  is  recjuired  when  the  die  or  tap  is  cutting  a  thread. 

The  edges  of  the  guide  fingers  which  come  in  sliding  contact  with  the 
driving  pins  as  sho\NTi  are  beveled  to  an  angle  of  lo  degrees  with  the  line 
of  travel  of  the  die  head.  This  angle  obviously  results  in  a  freer  forward 
movement  to  the  die  head  than  when  there  is  a  parallel  sliding  action, 
and  also  insures  the  lead  of  the  thread  conforming  very  closely  to  that 
of  the  die  or  tap.  The  angle  could  be  carried  to  such  a  spiral  as  to  tend 
to  push  the  sUding  head  foi-ward  immediately  the  die  has  caught.  The 
l')-degrce  slope,  however,  has  proved  very  satisfactory. 

At  /  is  shown  a  spring  cushioning  plunger  which  prevents  undue  shock 
when  catching  the  first  thread  on  the  w'ork,  and  is  especially  efficient 
when  cutting  threads  finer  than  32  per  inch. 

ADJUSTMENT    FOR    LENGTH    OF   THREAD 

Positive  and  uniform  length  of  the  thread  being  cut  is  insured  by 
adjusting  the  .self-locking  stop  screw  g.  This  stop  screw  determines  the 
amount  of  travel  which  the  die  head  a  may  have  without  rotating  with 
the  work.  For  instance,  should  it  be  desired  to  cut  a  ij-inch  length  of 
threatl,  it  is  only  necessary  to  adjust  the  nut  forward  until  the  amount 
of  lap  which  the  driving  pins  c  c'  have  on  guide  fingers  b  b'  is  equal  to 
I  inch,  as  indicated  at  /(. 

After  the  die  head  has  traveled  forward  enough  to  free  the  driving 
pins,  no  further  thread  cutting  occurs,  as  the  die  head,  then  being  free, 
revolves  with  the  work.  Wiien  the  spindle  and  work  are  reversed  the 
die  head  usually  reverses  also  until  tlie  lip  on  the  groove  in  the  die  head 
at  i  comes  in  contact  with  the  spring-actuated  pawl  /.  Tliis.  of  course. 
l)revents  further  reverse  rotation  of  the  (.lie  head,  and  as  the  work  con- 
tinues to  rotate  the  die  is  unscrewed. 

In  case  the  die  head  due  to  its  inertia  does  not  reverse  with  the  work 


208 


SCRE^\    MACHINE   I'APS   AND   DIES 


ADJUSTMENT   FOli   LENGTH  OF  THRJCAI)  209 

(as  docs  happen  occasionally),  and  should  the  driving  pins  and  fingers 
in  this  event  he  in  direct  line,  there  is  no  danger  of  strip|)ing  the  threads, 
for  the  guide  fingers  as  before  nientioneil  will  under  tliese  conditi(jns  be 
causctl  to  swing  outward  during  the  backward  movement  of  the  head 
by  the  driving  pins. 

A  light  si)iral  spring  A*  serves,  when  the  die  is  not  cutting  threads,  to 
hold  the  die  head  back  in  the  body  with  cushioning  plunger  against  the 
stop  screw.  ;ind  in  use  has  the  advantage  of  jireventing  the  marling  of 
the  first  few  threads  on  the  work  when  backing  off  the  die  providing  after 
the  thicad  has  been  cut,  and  previous  to  reveistil  of  the  work,  the  turret, 
together  with  the  holder,  be  pulled  backward  a  distance  ecjual  to  a  couple 
of  threads.  This  causes  the  spring  to  be  in  tension,  and.  after  the  spindle 
has  ijeen  reversed  and  the  die  unscrewed  fiom  the  end  of  the  woik,  the 
spring  brings  the  tlie  head  and  die  clear  of  the  end  of  the  piece  that  has 
been  threaded. 

On  account  of  the  fact  that  absolute  alinement  of  turret  and  spindle 
is  not  always  retained  and  as  dies  spring  in  hardening,  a  slight  floating 
action  i)etween  the  sliding  die  head  and  body  is  allowed.  Referring  to 
the  detail  of  the  head,  it  will  be  seen  that  the  shank  is  U.43o  inch  diameter 
while  the  hole  in  the  botly  is  0.437o  inch. 

In  some  cases  where  old  machines  are  used,  considerably  more  than 
this  freedom  may  ])e  advisal)le;  too  much  freedom,  however,  is  bad,  for 
then  trouble  mav  result  in  starting  on  the  die. 


CHAPTER  XXV 
Forming  Tools  and  Methods  of  Making  Them 

Quite  a  variety  of  types  of  cutting  tools  and  holders  have  been  devel- 
oped for  cross  forming  work  on  the  automatic  screw  machine. 

For  l^rass  work  flat-formed  blades  such  as  shown  in  Fig.  228  or  solid 
forged  tools  as  in  Fig.  229  are  found  very  satisfactory,  owing  to  its  being 
possible  to  obtain  with  these  perfect  side  and  peripheral  clearances. 

Where  frequent  sharpening  of  the  tool  is  required  and  where  the 
form  produced  must  be  kept  uniform,  these  tools  are  not  always  satis- 
factory, and  a  tool  whose  cutting  edge  can  be  sharpened  without  any 
alteration  to  its  contour  is  generally  preferred.  Fig.  230  illustrates 
what  is  usually  known  as  a  circular  forming  tool.  The  grinding  is  done 
on  face  a  h  c  d,  the  form  as  indicated  extending  entirely  around  the  per- 
iphery. Fig.  231  illustrates  another  type  of  forming  tool  which  admits 
of  the  cutting  edge  being  re-ground  without  alteration  of  its  contour. 
This  is  known  by  various  names,  a  very  common  one  being  "  dovetail 
forming  tool  "  from  the  fact  of  its  generally  having  a  dovetail  to  fit  into 
its  holder.  To  prevent  any  confusion  this  tool  will  be  referred  to  as  a 
dovetail  forming  tool  hereafter  in  this  chapter.  These  tools  are  generally 
held  and  fed  in  such  a  manner  that  the  cutting  edge  is  on  a  radial  line 
with  the  work  being  formed.  In  some  special  cases,  however,  it  is  fovmd 
more  satisfactory  for  the  tool  to  travel  tangentially  to  the  work  instead 
of  radially. 

COMPARISON    OF   TYPES 

There  are  various  things  to  be  taken  into  consideration  when  deter- 
mining whether  to  use  a  circular  or  a  dovetail  forming  tool,  and  the  fol- 
lowing points  may  be  of  assistance  when  making  the  decision: 

1.  The  peripheral  clearance  angle  being  constant  in  both  circular 
and  dovetail  tools,  as  shown  by  Fig.  232,  it  is  clear  that  in  the  dovetail 
type  there  is  more  metal  directly  under  the  cutting  edge  than  in  the  cir- 
cular tools  to  conduct  away  the  heat  which  is  produced  while  forming. 

2.  The  difficulty  and  cost  of  producing  an  accurate  and  smooth  form 
leave  much  in  favor  of  the  circular  forming  tool. 

3.  The  type  of  tool  post  required  for  a  circular  forming  tool  oftentimes 
interferes  with  turret  tools  simultaneously  operating  on  work  with  the 
cross-slide  tools.  The  dovetail  type  of  tool  permits  of  the  use  of  holders 
which  do  not  thus  interfere. 

210 


COMPARISON  OF  TYPES 


211 


212  FORMING  TOOLS  AND   METHODS  OF   MAKING   THEM 

4.  The  increasing  peripheral  clearance  of  a  circular  forming  tool  per- 
mits a  lesser  angle  to  be  utilized  at  the  point  of  cutting  than  with  the  dove- 
tail type,  and  this  lesser  angle  has  a  tendency  to  prevent  chattering  on 
account  of  the  support  afforded.  With  the  dovetail  type,  stoning  the 
clearance  face  is  sometimes  resorted  to,  which  in  effect  gives  a  lesser 
angle  at  the  cutting  point,  as  indicated  in  Fig.  233  at  B. 

A  similar  result  with  the  circular  tool  without  stoning  the  clearance 
edge  is  obtained  by  properly  determining  the  relation  of  the  center  of 
the  cutter  to  the  center  of  the  work  as  shown  at  B' ,  Fig.  234.  Raising 
or  lowering  the  cutting  edge  of  the  tool  changes  the  clearance  angle 
and  incidentally  changes  the  form  produced.  Consequently  the  clearance 
angles  and  the  relation  of  the  center  of  the  cutter  holding  bolt  to  the  work 
center  are  points  wdrich  it  is  necessary  to  consider  carefully. 

DIAMETERS    AND    CLEARANCES 

With  a  given  material  the  larger  the  diameter  of  the  work  the  greater 
the  angle  of  clearance  required.  Clearance  angles  are  seldom  less  than 
7  degrees  and  seldom  over  12  degrees  except  on  work  out  of  the  ordinary 
run. 

Tho  diameter  of  circular  forming  tools  is  an  important  point  to  con- 
sidero  A  small  diameter  has  a  more  pronounced  change  of  clearance 
angle  than  a  large  diameter.  In  fact,  when  of  an  exceedingly  large  diam- 
eter the  circular  tool  approaches  in  cutting  action  the  dovetail  type  of 
tool. 

On  the  Pratt  &  Whitney  automatic  screw  machines  the  standard 
outer  diameters  of  circular  forming  cutters  are  as  follows: 

No.  0  machine.  If -inch  0.  D.  cutter. 

No.  1  machine,  2-inch  O.  D.  cutter. 

No.  2  machine,  2|-inch  0.  D.  cutter. 

No.  3  machine,  3-inch  O.  D.  cutter. 

In  order  to  obtain  suitable  peripheral  clearance  the  practice  is  to  locate 
the  center  of  the  cutter  above  the  center  of  the  work  as  at  C,  Fig.  235; 
the  tool  holder  being  bored  out  above  the  center  as  indicated  and  the 
forming  tool  milled  out  below  center  a  corresponding  amount  so  that  its 
flat  cutting  surface  is  level  with  the  center  of  the  work.  A  very  satis- 
factory amount  to  locate  the  circular  tools  above  center  and  cut  their 
working  edges  below  for  the  machines  just  referred  to  is  as  follows:  For 
No.  0  machine,  |  inch;  No.  1,  t\  inch;  No.  2,  x\  inch;  No.  3,  fV  inch. 

GETTING   THE    TOOL    DIAMETERS    AT   DIFFERENT    POINTS 

In  order  to  produce  a  circular  or  a»dovetail  type  of  tool  so  that  the 
contour  of  its  cutting  edge  is  such  as  to  produce  correct  work,  the  amount 
a  circular  tool  is  off  center  as  C  in  Fig.  235  and  the  clearance  angle  of  a 


TOOL  -MAKING   METHODS  L'l:; 

dovetail  tool  as  at  I),  Fig.  2'.V1,  must  be  known.     In  connection  with  the 
circular  type  of  tool  the  diagrams   Figs.  'I'M),  2o7,  2."js  and  'l'6\i  will  be 

NO.O    AUTOM.VTIC  FORMING  TOOLS  I?/'oUTSIDF,  DIA.  CUTTING  EDCE^"bELOW  CENTER. 

AMOUNT  TO  ADD  TO  APPARENT  DIAMETER  OF  CUTTER, 
EACH  GKADCAT10N=jOOOl(Tu^)liJCn. 


s 


^    e;     n    <« 

t     1     -1     -J 


«9    r-    00     e> 


sJ^^Si    I^Si?!^    M^S3S5 


E.VCII  (;ltAI>rATI<iN  =  ,0(»  (  Lijij  )  IXCII. 
DIFFEUENCE  IN  DIAMETER  OF  SAMPLE. 


FlO.   '2m. 


Diagram  for  Fimliiifr  .Vctiial  Diamotcr  of  Circular  I'oriiiiii";  Tools  for  P.  it 
W.  No.  0  Automatic 


found  conv(>nient  for  (luickly  ascertaining  the  diameters  of  the  various 
sections  of  the  tool.  The  method  of  using  these  diagrams  is  given  in 
Fig.  2:i7. 

Where  different  diameters  than  tiio.^e  given  in  the  diagrams  are  used, 
or  when  the  amount  the  cutter  center  is  set  off  from  the  work  center 
varies  from  the  diagrams,  the  folhjwing  formula  may  be  used  in  connec- 
tion with  Figs.  240  and  241: 


i  -=  g  -^  if  ■¥  a?  -  {:2a\^y^  -  c). 

To  compute  the  measurement  T  on  dovetail  tools,  Figs.  240  and  242, 

the  formula  would  be: 

T  =  a  (cosine  .4) 

Ten  degrees  is  a  veiy  common  clearance  for  dovetail  tools;  cosine  10° 
=  0.9X481. 

TOOL-MAKING    METHODS 

There  are  various  methods  employed  by  the  toolmaker  in  accurately 
making  circular  and  dovetail  forming  tools.  The  form  of  tool  has  con- 
siderable to  do  with  the  scheme  selected.  For  instance,  if  the  work  is 
entirely  without  curved  or  irregular  outline  the  tool,  if  circular,  would 
be  simply  turned  up  in  an  engine  lathe  to  the  correct  dimensions,  some- 
times making  allowance  for  grinding,  and  then  milling  out  a  section  for 
the  cutting  edge.  In  ca.se  the  cutter  in  question  is  of  the  dovetail  form 
and  has  been  correctly  dimensioned,  no  difficulty  will  be  experienced  in 
accurately  planing  to  dimensions  if  the  toolmaker  has  proper  dimensioned 
size  blocks.  The  depth  micrometer  also  is  of  value  in  this  work.  Some- 
times fly  cutters  are  also  u.sed  for  making  these  dovetail  tools. 


214 


FORMING   TOOLS   AND   METHODS   OF   MAKING   THEM 


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IS- 


o 
H    °. 

^     II 

n  - 
o 

O 


-LV 

-or 

-eg* 
ceoo* 

6 

__| — 02* 

-IT 


H 
^^ 

!z;    CO 

IS  *=" 

2  p 

O    W 


— Og-  c   I 


STOO*    — Gf 

~ — sr 

" — IV 
-Of 

— ei' 

-n* 

-sr 

I — zv 

-TT 

-I OT' 

-co- 


-90- 

—SO* 
-w 

—80- 

-zo* 

J — TO- 


o  a 
'i  fa 

H     fa 


Tin:  tuansii:r  scheme 


217 


THK    THANSI'KU    S(  IIK.MK 

It  sometimes  liappcns  that  ciicular  cutters  arc  to  bo  made  wliich  arc 
vcrj'  difficult  to  caliper;  it  is  then  (piitc  frcviucnth"  a(lvisal)le  to  turn  a  tool- 
sotting  }iap;o  of  the  correct  (litimotor  and  copper  plate  the  gajie  (usinj;  blue 
vitriol),  and  tiien  to  size  the  cutter  correctly  by  first  brinpnij;  a  master 
tool  into  contact  with  the  gage,  noting  the  grailuation  on  the  micrometer 
collar  on  the  feed  screw  of  the  lathe,  then  moving  the  carriage  longitu- 
tlinally  and  bringing  the  master  tool  down  upon  the  cutter  to  the  same 
position.  This  scheme  admits  of  several  master  tools  being  used,  and  in 
connection  with  microm(>ter  stops  or  suitable  size  blocks  for  the  longi- 
tudinal movement  of  the  carriage  accurate  circular  tools  can  be  cconom- 
icaih"  made. 


Fot  Dovvtail  Tools 
Ealar^tl  HtictlOQ 

FIG. 242 


(    ' 


FIG.  :!4o 


FIG.  241 


Finding  Cuttiiifi  Depths  of  Forming  Tools 


Fig.  243  illustrates  this  transfer  scheme,  corresponding  numbers 
indicating  corresponding  diameters  of  model  and  cutter.  By  simidtane- 
ovisly  using  a  fixed  dead  tool  arranged  as  a  stop  on  center  against  the  gage 
before  referred  to  ami  a  master  tool  off  center  the  amount  the  circular 
cutter  is  off  from  the  work-center,  the  gage  may  be  made  of  such  diam- 
eters as  would  be  cori'ect  willi  the  cutting  edges  of  tiie  circular  cutter 
on  the  radial  line  instead  of  being  off  center.  Another  modification  of 
the  scheme  is  to  dispense  witii  the  dead  tool  or  stoj)  n^ferred  to  and  use  a 
rigid  master-tool-iiolding  block  capable  of  rapiil  vertical  adjustment 
which  will  jM'rmit  of  setting  the  master  tools  to  the  gage  while  on  center 
and  then  allow  them  to  l)e  dropjXMl  ])elow  center  an  amount  e<iual  to  the 
anioimt  the  cutting  edge  of  the  cutter  is  off  center.  This  pcnnits  very 
accuiate  cutters  to  be  jiroduced.      l"ig.  244  will  give  an  idea  of  this  method. 

Sometimes  it  is  found  convenient  first  to  rough  out  the  circular  form- 
ing tool  and  next  mill  out  the  space  foi-  the  cutting  edge,  and  thus  permit 


218 


FORMING   TOOLS   AND   INIETHODS   OF   MAKING   THEM 


the  master  tool  to  be  used  without  the  chance  of  error  creeping  in  which 
might  occur  on  account  of  the  necessity  of  moving  the  cross  shcle  of  the 
carriage  in  and  out. 


1st.  Make  Blank 


2nd.  Rough  out  with 
Ordinary  Latha  Tools 


3rd.  Finish  Eorm  with  Master  Tool, 


FIG. 


Makins;  Circular  Forminc;  Tools 


It  will  be  found  of  advantage  to  use  tissue-paper  feelers  between  the 
master  gages  and  the  tools  in  these  transfer  methods.  Some  toolmakers 
prefer  merely  copper  plating  the  master  and  just  burnishing  the  copper 
surface  to  show  contact  previous  to  transferring. 


MAKIXr.    DOVKTAIL   TOOLS  219 

MASTER    TOOLS    AND    TEMPLETS 

WluMi  invfiular  shaiK'<l  circular  formiiifj;  tools  aro  produced  hy  direct 
niirrcjuieter  measurements,  the  master  tool  is  «fenerally  made  of  the  same 
contour  as  the  work  that  is  to  bo  produced;  conse(juently  the  master  tool 
when  finishino;  the  circular  tool  must  be  held  off  centei-  an  timount  equal 
to  the  amount  the  cuttin<i  ed<fe  of  the  circular  tool  is  off  center.  The 
se(|uence  of  operations  in  making  a  circular  tool  from  a  given  model  or 
drawing  is  shown  in  Fig.  24.").  First  is  prepared  a  master  tool  templet 
--1,  and  then  a  master  tool  B.  The  templet  is  of  sheet  steel  and  should 
be  made  from  a  rectangular  piece  that  is  perfectly  scjuarc  to  facilitate 
measuring  with  a  micrometer.  Con.siderablc  skill  is  re(juired  to  file 
complicated  forms  accurately.  The  master  tool  B  is  shaped  exactly  to 
fit  the  master  tool  templet  .1,  and  is  also  made  perfectly  scjuare  to  pemiit 
measuring  with  a  micrometer. 

The  circular  tool  is  formed  by  the  latter  as  previously  outlined  anti  as 
shown  in  Fig.  24").  Owing  to  the  thin  scraping  chips  taken  when  fini.sh- 
ing  a  cutter  to  exact  size  the  master  tool  may  have  a  tenilency  to  glaze 
instead  of  cutting.  The  u.sc  of  turpentine  prevents  the  glazing  by  a.ssist- 
ing  the  tool  to  take  hold  on  very  thin  chips.  In  some  ca.ses  two  or  more 
ma-ster  tools  are  found  more  convenient  than  the  one,  especially  in  making 
wide  circular  forming  tools,  and  in  this  event  it  is  customary  to  make  a 
male  sheet-steel  gage  D,  Fig.  240,  for  convenience  in  testing  the  longi- 
tudinal positions  of  the  various  cuts  in  the  circular  tool.  This  latter 
gage  does  not  recjuire  the  complete  ionn  as  it  is  commonly  used  for  longi- 
tudinal work  onlv. 

M.VKING    DOVET.VIL    TOOLS 

In  planing  dovetail  tools  size  blocks  may  be  u.sed  as  already  men- 
tioned for  setting  the  planer  or  shaper  tool  to  the  various  hights  required. 
A  stop  screw  may  be  located  as  at  a,  Fig.  247,  and  size  blocks  useil  as  at 
b  for  regulating  the  setting  of  the  head.  Or  a  tlepth  micrometer  may 
be  u.setl  instead  of  the  stop  screw,  ti.ssue-pai)er  feelers  being  u.swl  in  either 
ca.se.  Size  blocks  may  also  be  u.sed  directly  on  the  plate  in  nuiny  cases, 
the  tool  being  brought  down  into  contact  with  the  different  blocks  for 
getting  the  depths  of  the  various  grooves,  etc.,  in  the  cutter  blank. 

In  using  a  formed  tool  of  same  contour  as  the  model  in  planing  the 
dovetail  tool  as  in  the  enlarged  sketch  in  Fig.  247.  the  formed  tool  is  held 
in  the  post  at  the  same  angle  as  the  dovetail  tool  will  afterward  l)e  used 
on  the  work.  The  dotted  lines  indicate  the  angle  to  which  the  work- 
ing edge  will  be  fini.shed  and  the  planing  tool  is  shown  set  at  the  same 
angle. 

Ill  planing  th(^  dovetail  form  of  tools  it  will  som(>times  W  fouml  of 
advantage  to  plane  the    face  of  the  cutting  edge  of  the  blank   to    the 


220 


FORMING   TOOLS   AND    METHODS   OF   MAKING   THEM 


TOOL    POSTS  221 

corrof't  anjiulrtr  relation  to  the  clcaranco  face  as  at  .1,  Fi<;.  21S^  and 
tlieii  scrilx'  the  eoiitour  desired  on  this  cuttinji  face  from  a  templet. 

if  the  teniplft  is  fastened  to  a  l)l()ck  as  sliown,  the  siuipe  of  the  finished 
soft  cutter  may  also  l)e  nicely  tested  as  in  Fiji.  21!). 

As  fre(|uent  hardeninji;  and  annealinf;  of  tool  steel  is  liable  to  affect 
its  (luality.  vaiious  expedients  are  resorted  to  ni  order  to  test  the  cor- 
rectne.ss  of  tools  without  undue  waste. 

TE.STING    OUTLINE    OF    FOHMIXC;    TOOLS 

A  common  scheme  is  to  mill  the  circular  tool  as  in  Fi<j;.  2.")0,  where  o  is 
the  actual  cutting-  e(l<;-e  and  h  a  trial  cuttinu  edjic.  The  cutter  is  hardened 
at  b  oid\'  and  a  piece  of  work  is  foinied  l)y  this  ed<2;e.  If  incorrect,  the 
cutter  edge  is  annealed  at  that  |)oint  and  then  corrected.  Another  method 
is  to  insert  a  Hat  piece  of  steel  as  in  Fig.  2.")1,  and  after  forming,  the  test 
piece  is  removed  and  lianlened  to  test  the  accuracy  of  the  form  in  the 
cutter. 

A  glass  i)late  is  freciueiitiy  found  convenient  when  testing  the  outline 
of  a  circular  tool  with  a  tempk't,  the  sketch,  Fig.  2.")2,  showing  the  appli- 
cation clearly. 

Narrow  circular  cutting-(jff  tools  and  in  fact  almost  all  ilelicate  cir- 
cidar  forming  tools  which  an^  apt  to  be  cracked  ])y  hardening  are  Ijene- 
fited  by  having  radial  slots  milled  as  shown  in  Fig.  2.")3,  they  are  then 
less  liable  to  crack  than  when  left  solid. 

TOOL    POSTS 

Tiierc  are  nuuiy  types  of  tool  posts  for  holiling  cro.ss-forming  ami 
cutting-off  tools.  Fig.  254  is  a  form  of  post  made  by  the  Pratt  &  Whitney 
Company  for  holding  circular  forming  tools.  This  has  an  adjustable 
swivel  tongue  or  guide  .1  which  is  controlled  by  an  eccentric  pin  B. 
The  cutter  is  doweled  to  the  tool  holder  ('  by  pin  I)  and  the  holder 
after  the  cutter  has  been  brought  in  to  convn-t  position  is  firndy  clamped 
to  the  tool  i)ost.  There  are  a  number  of  hok's  in  the  tool  holder  ('  which 
pernnt  the  cutter  to  be  doweled  until  entirely  worn  out.  The  holder 
is  clamped  by  screw  A',  and  being  considerably  further  from  the  center 
of  the  cutter  than  the  cutting  edge  insures  rigidity  in  this  respect. 
The  cutter  and  holder  fuithermorc  are  dampcvl  by  the  center  tool  binder 
/•'.  -V  gage  for  fiui<-kly  locating  the  cutter  edge  on  center  is  part  of  this 
eiiuipment.  Fig.  2.'),")  illustrates  a  pair  of  these  posts  in  position  ami  a 
gage  is  shown  at  f/  in  the  drawing. 

Fig.  2.")()  illustrates  a  circulai'  forming-tool  holder  with  two  varying 
diameters  of  tools  which  has  been  u.sed  on  automatics  e<|uip)>ed  with 
nuigazines  for  cast-iron  sewing-machine  hand  wheels  and  similar  work 
where   considerable   vaiiation    in    diameteis   would    recpure   a   very   large 


222  FORMING   TOOLS   AND    METHODS   OF   MAKING    THEM 


Fig.  254.  —  Adjustable  Tool  Post  for  Circular  Forming  Tools 


Fig.  255.  — Adjustable  Tool  Posts  for  Circular  Forming  Tools 


TOOL   POSTS 


223 


circular  tool   of  the  ordinary   ty))c\   wiiich   would    bo    unsatisfactory  as 
rcfiards  jx-riphcral  clearances. 

Fig.  2.37  is  a  coniin(»ii  d<)\ctail  tool  lujlder  ami  post.     Fig.  258  repre- 


I'lu.  2.30.  —  Tool  Posts  tor  T\V(j  ('ireular 
Tools 


sonts  another  style  of  tool  post  for  holding  the  dovetail  type  of  tool. 
Fig.  2.)9  shows  a  tool  post  for  holding  flat  tools.  The  tool  is  damped 
by  screws  a  in  swinging  bloc-k  b  which  is  adjusted  by  screws  c  and  damped 


N 


For  Biii.liiis!  Screwi 


y 


l'i(i.  _'.")7.  —  Post  for  Dcivctail  Tool  Holder 


fast  with  the  tool  post  to  the  cross  slide  by  nut  d.  An  eccentric  pin  e, 
adjusts  the  tool  to  position  vertically,  and  the  .'^winiiinjj;  block  gives  the 
re(juired  adjustment  for  side  clearance. 

Tiiere  are  numerous  other  types,  where  pi-ovision  is  made  for  adjust- 


224 


FORMING    TOOLS   AND   METHODS   OF   MAKING   THEM 


ing  the  tool  vertically  by  wedges,  swinging  anvils,  etc.     Fig.  260  illus- 
trates one  of  these  posts  with  swinging  anvil. 


Fig.  258.  —  Dovetail  Forming  Tool  Post 


APPLICATION    OF    TOOLS    TO    WORK 


Generally,  circular  dovetail-forming  tools  do  not  have  perfect  side 
clearance.  This  feature  is  discussed  in  Chapter  XXVII  on  "Why  Chips 
Cling  to  Screw  Machine  Tools." 


Fig.  2.59.  —  Post  for  Straight  Cut-off  and 
Forming  Tools 


One  point  that  should  be  carefully  considered  in  the  use  of  cross-form- 
ing tools  is  whether  it  is  most  desirable  to  use  a  tool  with  the  forward  or 
reverse  movement  of  the  spindle.  This  is  of  particular  importance  when 
the  forward  and  reverse  speeds  are  greatly  at  variance,  which  is  generally 
the  case,  as  the  production  per  hour  may  be  greatly  increased  or  decreased 
according  to  these  conditions.  The  question  as  to  whether  a  cross-feed- 
ing tool  is  to  be  in  cutting  action  simultaneously  with  an  opposite  cross- 
feeding  tool,  or  with  a  tool  in  the  turret,  is  also  to  be  considered  in  their 
connection. 


r<)RMi.\(;  AM)  rri{M.\fj  225 

Fig.  201  illustrates  a  viuii'ty  of  work  wliicli  is  common  to  the  auto- 
matic screw  maciiinc  and  shows  various  arrangements  of  f(jiining  tools, 
seveial  of  which  are  adapted  for  simultaneous  operations  of  front  and 
rear  tools  which  many  times  is  conducive  to  a  high  rate  of  production 
as  the  cuts  taken  with  each  tool  may  bo  greater  than  if  either  were  operat- 
ing alone  as  the  side  pressure  on  the  work  is  iKilanced.  When  the  c(m- 
struction  of  the  nuichine  tloes  not  permit  of  the  simultaneous  cutting 
action,  a  similar  arrangement  of  tools  is  satisfactory;  only  the  time  and 
sequence  of  their  operations  must  he  taken  into  consideration. 


Fiu.  JOU.  —  Tool  Post  with  Adjustable 
Shoe 


FORMING    AND    TURNING 

There  arc  a  number  of  important  iletails  regarding  the  shape  and 
method  of  using  forming  tools  some  of  which  will  now  i)e  touched 
upon:  Sketches  A,  A^,  A-,  Fig.  261,  indicate  a  method  of  forming  and 
cutting  off  a  piece  with  two  tools,  one  of  which  is,  of  coui.se,  fed  into  the 
work  before  the  other.  The  burs  indicated  by  arrow  points  at  .1-  are  due 
to  the  rubbing  of  tiie  forming  tools  on  the  side  cuts,  and  unless  there  Is 
perfect  side  clearance  to  the  forming  tool,  the  bur  will  be  increased.  By 
adding  a  bevel  edge  to  the  tool,  as  shown  l)y  ,1,  the  bur  produced  is  re- 
removed.  ,1*  is  a  refinement  over  .1.  M  B  is  illustrated  a  common 
method  of  sinudtaneously  cutting  off  and  forming  shoidder  screws,  the 
tw(j  tools  finishing  their  cuts  at  the  same  tim(\  Where  a  machine  with 
single  cross  slide  is  used  for  producing  work  in  this  fashion,  the  cutting- 
off  tool  should  precede  the  forming  tool  as  the  l)ar  then  has  its  full  diam 


226  FORMING   TOOLS   AND   METHODS   OF   MAKING   THEM 


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MAKL\(J    SHORT   SCKKWS   AND    OTlIlii;    I'AUTS  227 

etor  and  strono;th  for  the  cuttin<i;-ofF  operation.  Sketches  ('  to  C'  sliow 
an  ordinary  screw  in  which  the  head  is  to  be  formed  l)y  cross-slide  tools 
and  the  body  tuiiied  by  a  box  tool  or  hollow  mill  in  the  turret.  The 
cross-slide  tools  start  their  cuts  togethei',  but  the  forminji  tool  for  the 
head,  of  course,  has  to  finish  first.  The  cuttinfi-cjff  tool  shoidd  be  made 
so  as  to  ])e\'el  the  end  of  the  bai'  as  shown,  in  ordei-  to  permit  the  starting 
of  the  box  tool  on  a  lijiht  cut  luitil  its  back  rest  lias  a  good  support. 

The  forming  cutter  for  the  head  should  l)e  beveled  as  at  r  in  C''  in  case 
tlic  box  tool  follows  tile  forming  cut.  This  allows  the  tool  to  cut  luio 
the  stock  as  at  ('-.  leaving  a  beveled  shoulder  so  that  when  the  box  tijol 
is  fed  along  it  comi^letely  removes  the  su])erfluous  metal  without  leaving 
an  objectional)l('  ring  whicii  is  (piite  apt  to  be  pi'oduced  undei"  the  con- 
ditions represented  in  C'^  and  ('''.  The  ring  of  metal  there  seen  which  is 
a  residt  of  the  scpiare  shoulder  cut  by  the  forming  tool  in  C*,  is  (piite  apt 
to  tip  over  on  the  screw  blank  and  cramp  and  t(;  later  on  i)revent  the  tlio 
from  cutting  the  thread  ])roperly. 

sii'i'OHTiNc;  i.dxc;  work 

At  J)  is  illustrated  a  method  of  forming  and  cutting  off  long  pieces 
where  it  is  generally  advisable  to  use  a  supporting  device  as  indicated. 
It  is  obvious  that  tiie  two  cross-slitle  tools  are  not  u.scd  sinudtaneously 
in  this  case.  The  bevel  at  I)  left  b}'  the  first  tool  prevents  the  work 
breaking  off  prematurely.  A'  is  a  very  simjjle  piece  to  produce,  ^^'here 
there  arc  double  slides  on  the  machine  the  two  tools  may  start  their  cuts 
at  the  same  time,  but  the  rear  tool,  of  cour.se,  merely  chamfers  the  edges 
of  the  work.  This  bevel  cutter  is  a  r(>finement  not  always  reciuiretl,  but 
it  is  desiral)le  when  the  l)ui'  wiiich  would  l)e  produced  by  the  front  tool 
is  objectionable. 

M.\KIN(;    SHORT    S(1{KWS    AM)    OTHEIt    P.VHTS 

At  F,  F\  F-  antl  F^  are  shown  several  methods  of  forming  and  cutting 
off  short  screws.  The  method  at  F  is  a  rapid  one  and  is  particularly 
reconnnended  for  machines  with  one  cross  slide,  the  cutting  olT  of  the 
finished  screw  being  accomplishe(l  at  the  same  time  the  forming  of  a  ni'w 
blank  is  being  done  and  re(iuiring  a  traverse  movement  of  only  about 
one-half  the  radius  of  the  work.  /•''  and  F'-  are  applicable  only  to  a 
machine  with  double  cross  slides  in  case  sinudtaneous  cutting  action  is 
(lesir(>d.  These  two  methods  are  rajiid.  both  tools  finishing  their  cuts  at 
the  same  time.  /•"-  recpiii'es  a  more  costly  tool  outfit,  but  on  accovmt  of 
balancing  the  cut  is  preferrecl  wheic  coarse  feeds  are  taken  or  long  work 
is  to  be  formed.  The  method  of  i)roducing  short  screws  indicated  in  h^ 
makes  u.se  of  a  rear  cutting-olf  tool  after  tlie  forming  tool  has  completed 
its  work. 


228 


FORMING  TOOLS  AND  METHODS  OF  MAKING  THEM 


G  illustrates  a  scheme  which  is  of  value  where  roughing  antl  finishing 
cuts  are  required  on  exceedingly  accurate  work.  The  roughing  tool  cuts 
off  the  piece  previously  formed  and  leaves  a  light  cut  for  the  finishing 
tool  to  take  on  the  work  outlined.  H  is  self-explanatory,  indicating  the 
value  of  the  turret  support  for  the  work. 

A    PAIR    OF    DOVETAIL    TOOLS 

A  method  is  shown  in  Fig.  262  for  getting  perfect  side  clearance  in 
dovetail-forming  tools.     The  front  tool  is  used  for  finishing  the  left-hand 


Fig.  262.  —  Forming  with  a  Pair  of 
Dovetail  Tools 

sides  of  the  work  flanges  and  the  rear  tool  for  finishing  the  right-hand 
sides  and  the  end,  the  tools  being  inclined  in  opposite  direction  so  as  to 
obtain  clearance  for  these  cuts.  The  tools  are  cut  out  as  indicated  by 
the  arrows,  at  diagonally  opposite  points  so  that  each  cutter  will  clear 
the  surfaces  finished  l^y  the  cutter  opposite.  Similarly,  side  clearance 
to  circular  tools  is  possible  by  inclining  their  axes. 

ARRANGEMENT    OF    CIRCULAR    TOOLS 

In  Fig.  2(33,  sketches  /,  K,  L,  M  show  various  ways  of  arianging 
forming  tools  with  reference  to  the  direction  of  rotation  of  the  spindle. 
These  are  to  be  considered  as  being  viewed  from  the  turret,  looking  toward 
the  head  spindle.     The  arrangement  at  /  is  a  most  common  one  when  a 


ARRANGEMENT   OF   ClRdLAR   TOOLS 


229 


spring  .screw  div  or  a  tap  is  to  he  used.  The  low-speed  forward  drive  of 
the  spintUe  i.s  used  for  the  cro.ss  forniinji;  of  the  work  (a.s  at  C'-C,  F-F^, 
Fig.  201),  while  the  high  icver.se  speed  is  utilized  for  removing  the  die 
or  tap  and  for  light  cut  ting-off  cuts  like  that  at  F'.  At  A'  is  a  .similar 
arrangement  to  J ,  and  in  some  ca.ses  this  is  substituted  for  the  former, 
particularly  wheie  llic  die  or  tap  has  a  left-hand  thread;  the  cutting-off 
tool  is  used  at  the  front  and  the  heavier  forming  cuts  taken  from  the 
rear  in  this  event. 


Fig.  26o.  —  Foriiiiii":  Tool  Positions 


/.  and  .1/  show  ai'rangement  of  tools  where  they  operate  siniultanecnisly 
or  wliere  there  is  no  necessity  for  reversing  the  direction  of  rotation  of 
the  heatl  .spindle.  In  this  latter  case  the  spindle  .speeds  generally  differ, 
and  by  carefully  selecting  tlie  i)roper  speeds  a  high  rate  of  production 
will  be  possible.  In  all  cros.><-forming  work  it  is  essential  that  the  spindle 
fit  snugly  in  its  front  l)earing  and  that  the  collet  or  chuck  has  a  good 
parallel  contact  witli  the  bar  which  is  being  foi-med.  A  bell-mouthed 
collet  is  most  fre([uently  the  cause  of  chatteiing,  altliough  excessive 
clearance  may  also  j)romote  chattering. 

The  tool  holder  shoukl  l)e  of  such  design  as  to  hold  the  tool  fiinil}' 
and  the  cro.ss  slide  of  such  dimensions  and  so  gibbed  as  to  permit  of  no 
spring  or  shake.  With  careful  attention  to  the.se  details  and  providing 
the  cuts  are  supported  from  the  turret  when  they  are  wide,  and  also  ]3ro- 
viding  the  design  of  the  tool  and  the  question  of  clearances  are  carefully 
considered,  excellent  results  should  be  obtained. 

The  rates  of  feed  and  the  subject  of  lubricants  are  discus.-<ed  in  other 
chapters  of  this  book.  Obviously  .speetls,  feeds,  and  lubrication  all 
have  an  im]iortant  bearing  on  results  obtained  in  the  automatic. 


CHAPTER  XXVI 

NuRLiNG  Tools  and  Their  Applications 

NuRLiNG  in  the  screw  machine  may  be  accomphshed  in  several  ways. 
The  softer  materials  such  as  rod-brass,  etc.,  due  to  the  greater  mobility 
of  the  metal  permit  of  deeper  and  coarser  pitch  nurling  than  the  harder 
and  more  brittle  metals. 

operation  of  the  nurl 

Generally  speaking,  the  nurling  tool  which  is  a  hardened  tool  steel 
roll,  with  impressions  on  its  periphery  the  reverse  of  those  desired  on  the 
work,  is  allowed  to  rotate  freely  when  brought  into  contact  with  the  blank 
that  is  to  be  nurled.  In  some  instances,  however,  long,  fancy  impressions, 
numbers  or  letters  are  to  be  nurled  upon  blanks,  and  in  this  event  precise 
results  are  insured  by  coupling  the  nurl  to  the  work  spindle  by  gearing, 
so  as  to  revolve  it  positively  at  a  correct  uniform  speed. 

In  addition  to  producing  fancy  corrugations  by  nurling,  short  threads 
are  successfully  rolled  in.  In  typewriter  manufacturing  establishments 
it  is  common  practice  to  burnish  short  sections  of  studs  and  shoulder 
screws  to  size  by  passing  across  the  work  two  cylindrical  hardened  and 
ground  rolls,  which  are  separated  to  give  the  exact  diameter  desired. 

METHODS    OF    NURLING 

Referring  now  to  the  more  common  nurling  operations,  there  are  three 
methods  to  consider. 

Method  A.  Nurling  from  the  turret  by  use  of  a  holder  carrying  two 
or  more  narrow  nurls  which  may  be  adjusted  radially  to  suit  the  work. 
These  nurls  are  passed  longitudinally  over  the  work.  Figs.  26-i  and  265 
illustrate  two  types  of  these  tools. 

Method  B.  Nurling  from  the  cross  slide  by  use  of  a  holder  carr^'ing 
one  or  two  nurls,  and  forcing  the  nurl  radially  into  the  work.  This  is 
illustrated  at  a  and  6,  Fig.  266. 

Method  C.  Nurling  from  the  cross  slide  by  means  of  a  holder  carr3'ing 
a  nurl,  so  as  to  pass  tangently  across  the  work.  Fig.  267  illustrates  this 
type  of  holder  in  combination  with  a  cutting-off  tool,  the  nurling  opera- 
tion being  accomplished  first  and  the  cutting-off  following. 

230 


METHODS  OF  NURLING 


231 


Xurl  FIG.  266 


CD        CD 


=Oo| 

I  >url  Stud 


a 


FIG.   268 


CD     CD 

iiliia^SSl/ 

y 

fEsfH-^ 

1  \  Xurl  Studs 
/^Held  Here 

f,^.f  1  yJ 

Surl  Stud  Holder. 


r^^l— ' 


A 


FIG.  267 

Nurling  Tools 


FIG. 269 


232  NURLING   TOOLS  AND   THEIR   APPLICATIONS 


APPLICATIONS    OF    DIFFERENT    METHODS 

Method  A,  owing  to  the  absence  of  any  side  pressure,  is  recommended 
for  all  cylindrical  nurling'  operations  when  the  length  of  the  desired  im- 
pression is  greater  than  its  diameter.  In  fact  many  operators  use  this 
method  for  all  straight  work.  On  complicated  work  where  all  the  turret 
holes  are  required  for  the  various  cutting  tools,  it  sometimes  becomes 
necessary  to  use  holders,  which,  in  addition  to  holding  the  nurling  tools, 
are  so  arranged  as  to  hold  an  internal  cutting  tool  such  as  a  drill  or  coun- 
terbore.  The  holder  must  be  stiff  so  as  to  hold  the  nurls  to  the  work 
firmly  without  spring. 

Method  B  is  only  recommended  for  narrow  nurling  on  soft  metals 
close  to  the  end  of  the  head  spindle.  On  hard  materials  or  on  wide  work, 
the  excessive  pressure  required  to  force  the  nurl  into  the  work  is  apt  to 
crowd  the  work  away  and  produce  poor  results. 

Method  C  is  a  satisfactory  means  of  nurling  work  up  to  a  length  equal 
to  its  diameter,  providing  the  nurling  is  close  to  the  end  of  the  head  spindle. 
The  pressure  required  to  force  the  nurl  into  the  work  is  much  less  than 
by  method  B.  These  last  two  methods  permit  of  all  the  turret  holes 
being  utilized  for  other  operations,  and  as  shown  by  Fig.  267,  method  C 
permits  of  the  combining  of  the  nurling  and  cutting-off  operations  in  one 
holder.  Method  C  may  be  satisfactorily  used  for  nurling  work  as  in 
Fig.  268,  having  several  narrow  steps,  by  arranging  the  holders  to  carry 
three  nurl  studs  as  indicated  by  Fig.  269.  The  nurls  cut  one  after  the 
other,  and  thus  prevent  undue  pressure  due  to  simultaneous  action  upon 
the  work. 

END    NURLING    AND    BURNISHING 

In  addition  to  nurling  upon  the  periphery  of  work,  quite  frequently 
end  nurling  as  in  Fig.  270  is  required.  This  is  satisfactorily  accomplished 
by  means  of  a  turret  nurl  holder  carrying  a  bevel  nurl  at  a  suitable  angu- 
lar relation  to  the  work  as  shown  in  Fig.  271. 

The  method  of  applying  burnishing  rolls  to  short  studs,  scre-^s,  etc., 
as  referred  to  in  connection  with  the  manufacture  of  typewriter  parts, 
is  illustrated  in  Fig.  272. 

In  this  chapter  the  aim  has  been  simply  to  outline  the  various  methods 
and  to  point  out  where  they  might  be  successfully  used,  therefore  no  de- 
detailed  description  of  the  various  types  of  holders  or  of  methods  of 
making  nurls  is  given. 

RESULTS    OBTAINED 

All  of  the  methods  described  when  used  on  work  for  which  the}^  are 
recommended  should  give  excellent  results,  providing  the  nurling  of  too 
heavy  impressions  for  the  character  of  the  material  is  not  attempted, 
and  also  providing  the  work  is  turned  to  proper  circumferential  tlimen- 


RESULTS   OBTAINED 


233 


sions  so  as  to  mesh  well  with  the  pitch  of  the  nuiliii<i  tool  without  irreg- 
ular spacing  at  the  end  of  each  revolution.     A  slight  variation  in  the 


Fit;.  270 


iiurui6liiug  Uoll^ 


Barulsbiug  Boll' 


^    , 

1  1 

Size  Adjustiug  Block 

^. 

1  1 

Xurliiifi  uiul  liuriii.shing  Tools 

diameter  of  tlie  blank  oftentimes  results  in  a  marked  improvement  in 
the  appearance  of  the  ])iece  when  nurlcd,  especially  on  coarse  pitch  work. 
A  liberal  supply  of  lubricant  should  be  used  on  the  work  and  unneces- 
sarily high  speeds  avoided. 


CHAPTER  XXVII 
Why  Chips  Cling  to  Screw  Machine  Tools 

Clinging  of  chips  to  the  cutting  edges  of  tools  used  in  the  screw 
machine  or  under  similar  conditions  is  due  largely  to  the  heating  of  the 
chip  or  of  the  cutting  edge  of  the  tool,  or  both,  to  such  an  extent  as  to 
cause  the  chip  to  become  "welded"  to  the  tool. 

This  heating  may  be  caused  by:  (1)  Lack  of  sufficient  angular  clear- 
ance between  tool  and  work;  (2)  too  high  cutting  speed  and  consequent 
dulling  of  cutting  edge  of  tool;  (3)  insufficient  and  improper  cooling  or 
lubricating  material;  (4)  incorrect  rake  of  cutting  edge  of  tool;  (5)  lack 
of  chip  room;  (6)  too  much  non-cutting  tool  surface  in  contact  with  work. 

CLEARANCE 

Referring  to  the  matter  of  angular  clearance,  Fig.  273  gives  an  idea  of 
desirable  conditions  for  a  cutting-off  tool,  while  Fig.  27-4  illustrates  un- 
desirable conditions.  The  slight  flat  at  a,  Fig.  273,  is  to  insure  smooth- 
ness of  the  work.  In  case  circular  tools  are  used  in  the  ordinaiy  manner 
to  cut  down  a  form,  as  in  Fig.  275,  there  is  no  clearance  at  the  outer 
edge  of  the  cutter  at  b.  By  swinging  the  center  slightly,  as  shown  in  Fig. 
276,  so  that  the  axis  of  the  cutter  is  not  parallel  with  the  axis  of  the  mate- 
rial being  worked,  perfect  clearance  may  be  obtained.  When  one  tool 
is  used  for  cutting  both  sides  of  a  narrow  slot,  as  in  Fig.  277,  a  rectangular 
form  of  tool  is  generally  recommended,  as  complete  clearance  can  be 
obtained.  This  form  of  tool  has  a  relatively  short  life  as  compared  with 
the  circular  type  of  tool,  and  consequently  the  latter  with  its  partial 
clearance,  as  shown  in  Fig.  278,  is  commonly  used.  In  cases  where  it  is 
not  subjected  to  severe  duty  as  regards  cutting  speed,  good  results  are 
obtained.  When  the  width  of  the  slot  is  not  important,  each  side  of  the 
tool  may  be  finished  spirally,  giving  excellent  clearance  conditions,  as 
illustrated  by  Fig.  279.  The  clearance  should  be  ample  to  avoid  undue 
contact  with  the  work,  but  on  the  other  hand  not  be  so  much  as  to  pro- 
duce a  thin  cutting  edge,  as  the  latter  will  quickly  heat  under  working 
conditions  and  then,  becoming  soft,  will  rapidly  become  unfit  for  use. 
Furthermore,  chattering  may  result  from  too  much  clearance,  as  indicated 
at  A,  Fig.  282. 

It  should  be  obvious  that  internal  cutting  tools  require  clearance  as 

234 


CLEARANCE 


235 


O 


3 

o 


236  NURLING   TOOLS   AND   THEIR   APPLICATIONS 

well  as  external  tools;  in  the  former  case  not  only  the  cutting  lip,  but  the 
outer  diameters  require  back  clearance,  as  represented  in  Fig.  280. 

CUTTING    SPEEDS 

It  is  conceded  that  there  is  a  limit  to  the  cutting  speed  on  account  of 
the  edge  of  the  tool  giving  out  when  an  exceedingly  high  speed  is  at- 
tempted. There  is  also  a  limit  due  to  the  heating  of  the  chip  so  as  to 
cause  it  to  weld  to  the  tool.  Apparently  the  material  being  worked  has 
considerable  to  do  with  this  trouble ;  experience  shows  that  soft  low-carbon 
steel  and  brass  and  similar  materials  will  cause  the  most  trouble,  as  the 
welding  process  occurs  before  a  speed  destructive  to  the  cutting  edge 
has  been  reached.  On  harder  material,  i.e.,  cast  iron  or  steel  with  more 
carbon,  the  welding  is  not  as  troublesome. 

COOLING    AND    LUBRICATING    MATERIALS 

In  many  shops  "  good  lard  oil "  is  the  standard  prescription  for  use 
in  connection  with  external  and  internal  cutting  operations  on  cylin- 
drical work.  The  advantages  of  oil  are  fully  appreciated  when  the  ele- 
ment of  friction  plays  an  important  part  —  for  instance,  in  cutting  threads 
with  dies  or  taps,  and  in  some  other  internal  cuts  —  but  successful  results 
have  often  been  obtained  when  absolute  failure  seemed  apparent  by 
substituting  a  cooling  material  composed  largely  of  water  in  place  of  the 
oil. 

Oil  positively  will  not  conduct  away  the  heat  generated  by  high  cutting 
speeds  and  feeds  as  rapidly  as  many  of  the  numerous  cooling  materials 
on  the  market.  Oil,  as  compared  with  the  thinner  liquids,  is  sluggish 
in  penetrating  to  the  point  where  the  chip  is  being  torn  from  the  work. 

For  internal  work  a  compromise,  or  in  some  cases  the  clear  oil,  is 
more  desirable  on  account  of  the  fact  that  the  tools  do  not  generall}^ 
have  as  perfect  a  clearance. 

RAKE 

In  case  of  the  tool  having  negative  rake,  as  at  C,  Fig.  281,  the  chip 
will  be  pushed  off  instead  of  being  clean  cut  and  curled,  as  at  D.  When 
negative  rake  is  carried  to  extremes,  the  chip  which  is  being  broken  off 
may  be  drawn  between  the  cutting  edge  of  the  tool  and  the  work  and 
thus  become  wedged  and  heated,  and  welding  may  result.  The  wedging 
action  is  particularly  troublesome  on  internal  work,  and  may  frequently 
be  overcome  by  changing  the  type  of  the  flute  in  the  tool. 

In  cases  of  tools  having  excess  positive  rake,  as  in  Fig.  282,  the  cut- 
ting edge,  being  so  thin,  rapidly  heats  and  becomes  destroyed,  so  that 
this  condition  must  also  be  avoided. 

Clearance  and  rake  form  quite  a  deep  subject.  The  exact  amount 
depends  upon  the  nature  of  cut  as  well  as  upon  the  nature  of  the  mate- 


I{AKE 


237 


u 

CJ 

o 

o 


< 


238  NURLING   TOOLS  AND   THEIR   APPLICATIONS 

rial  being  cut ;  in  this  chapter  it  is  not  desirable  to  go  into  the  matter  at 
any  great  length,  as  it  has  been  treated  in  connection  with  various  classes 
of  tools  in  the  preceding  chapters  of  this  section.  The  point  to  be  empha- 
sized in  connection  with  the  subject  being  treated  is  that  the  cutting  edge 
must  not  be  given  too  acute  an  angle. 

CHIP   ROOM 

On  internal  cutting  tools,  when  there  is  little  chip  space,  the  packing 
or  wedging  of  chips  and  the  resulting  heat  cause  much  trouble,  particu- 
larly on  brass  and  similar  materials;  increased  chip  space  overcomes  the 
difficulty. 

The  form  of  cutting  flute  influences  greatly  the  welding  action,  and  in 
some  instances  the  spiral  of  the  flute  has  an  effect.  Where  a  long  chip 
causes  trouble,  a  straight  flute  or  sometimes  a  left-hand  spiral  is  more 
satisfactory  than  the  more  common  right-hand  spiral. 

The  cutting  edge  should  generally  be  radial,  as  at  E,  Fig.  283.  In 
case  it  is  ahead  of  the  center,  as  at  F,  the  chip  is  forced  outward  and 
against  the  work,  and  then  may  become  wedged  into  the  cutting  edge. 
Making  the  cutting  edge  slightly  below  center,  as  at  G,  where  a  straight 
flute  or  right-hand  spiral  is  used,  is  sometimes  recommended,  as  the  chips 
then  automatically  work  toward  the  center  of  the  tool,  and  are  then  forced 
out  from  the  front  of  the  hole  being  bored. 

When  wide  chips  cause  trouble,  the  cutting  edge  may  be  serrated  or 
broken  and  narrower  chips  produced. 

The  style  of  cutting  edge,  number  of  cutting  edges,  etc.,  are  second 
only  in  importance  to  clearance  and  rake,  and  much  is  to  be  learned  in 
this  direction. , 

SURFACE    IN    CONTACT   WITH    WORK 

The  difficulty  of  too  much  non-cutting  surface  in  contact  with  the 
work  is  experienced  mostly  with  internal  cutting  tools  and  particularly 
in  brass  and  bronze  work.  H,  Fig.  284,  illustrates  a  drill  correctly  relieved; 
K,  Fig.  284,  is  bad.  In  the  latter  case  the  material  being  worked  becomes 
welded  to  the  surface  L,  on  account  of  the  heat  caused  by  the  rubbing 
action  of  such  a  great  amount  of  contacting  surface. 

In  conclusion,  while  it  is  generally  the  practice  to  design  tools  to  suit 
the  material,  it  must  not  be  overlooked  that  a  slight  change  in  the  nature 
of  the  material  being  machined  will  oftentimes  make  possible  great 
improvement  both  as  to  quality  and  quantity  of  work  turned  out. 


INDEX 


A 
Acme  multiple-spindle  pages 

automatic  screw  machine    95-113 

box  tools  for     100,  108 

box  tools  with  roller  rests  10(5,108 

cam-shaft  drive    !)7-99 

chanjie-gear  system.  97 

capacities         ll^i 

countershaft  arrangement 111,112 

cross-drilling  attaelnnent     111,112 

cross-slide  cams    .    .  99 

cross-slide  mechanism     .      lOfi 

four  spindles  and  tool  positions  .  .      107 

indexing  mechanism      .  100,  101 

nurling  tools 109 

shaving  tools 107-1 10 

slotting  and  milling  attachments lll-ll-'i 

speed-change  mechanism    ...        97 

spindle  and  ehuckinsr  meehaiiism  .  .  100,  101 

spindle  drive     97 

spiridle  frictions    102 

spring  collets  and  feed  tubes   .  S',i,  107 

thread-rolling  tool    .  .  .  109,  110 

threading  mechanism  104,     10.") 

threading-spindle  change  gear  .      104 

tool-slide  cams 99,  103 

tools  for     1()()-113 

top  .slides     100 

work  spindle  cylinder  .  .9o,  96 

Alfretl  Herbert  automatic  screw  machine    89,  90 

tools  for     90 

Alfre.l  Herbert 

niaga/ine  automatic  .screw  machine     12."^-134 

details  of  magazine    129,  132 

spindle  and  chuck    129 

Angle  of  clearance  for  forming  tools     212,  213 

Angles  for  Pratt  tt  Whitney  cams,   calculations  for 1.5-18 

finding  graphically 18-20 

tal)les  of  correspomling  feeds 29-36 

chucking  cams    12 

indexing  cams  .  .  .        15 

stock-feed  cams    .  12 

turret-feed  cams  17-20 

239 


240  INDEX 

PAGES 

Arbor,  taper,  for  turning  spring  collets 173 

Attachment,  cross-drilling.  Acme    Ill 

end  and  side-milling,  Acme Ill,  112 

independent  cut-off,  Cleveland    73 

magazine  feed,  Cleveland 126,  127 

screw-slotting,  Brown  &  Sharpe      50 

slotting  and  milling.  Acme     113 

tap  and  die  revoh'ing,  Brown  &  Sharpe      49 

third  spindle  speed,  Cleveland     74 

Automatic  screw  machine 
(or  turret  lathe) 

Acme  multiple-spindle 95-113 

Alfred  Herbert 89,  90 

Alfred  Herbert  magazine 128-134 

Brown  &  Sharpe      37-51 

Brown  &  Sharpe,  with  constant-speed  drive 64-GG 

Cleveland 67-77 

Cleveland  double-spindle,  plain 93,  94 

Cleveland,  with  magazine  attachment 126,  127 

Gridley  multiple-spindle     119-125 

Gridley  piston  ring      144-146 

Gridley  single-spindle    78-87 

Gridley  single-spindle,  motor  operated 86-88 

Potter  &  Johnston     135-143 

Pratt  &  Whitney 3-11 

Prentice  multiple-spindle    147-155 

Spencer  double-turret 91,  92 

Universal  multiple-spindle 114-118 


B 

Belts,  lubrication,- etc.,  in  screw  machine  operation 161 

Boring  spring  collets    171 

tool,  adjustable,  Cleveland 75,  76 

Box  tool,  Alfred  Herbert    90 

cutters,  end-forming    185 

for  taper  work    184 

grinding     178 

radial 176 

rake  of     178 

sizes  of     185 

tangent    176,  185 

tangent,  adjustment  of     185 

Box  tool  rests  and  cutters       177 

boring  out     180 

burnishing  of  stock  with 180 

clearance  of 179 

cutting  out  corners    184 

for  long  and  short  work    ISO 

hardening  and  lapping    184 

lubrication  of    180 


l.NDLX  241 

I'AGES 

Hox  tool  rests,  making       164 

oix'ii      176 

roller      75,  HMi,  lOS,  ISl 

sfk'ctiou  of    17'J 

scttiiifi    17'),  ISO 

solid 178 

stem      179 

types  of 170-181 

width  of 184 

Box  tools.  Acme,    106,  108 

and  other  external  ciittiii';  appliances    175-186 

Brown  iV  Sharju-       47 

ImshiiiK    178,  17!) 

eoiKJitions  of  service    175 

finishing,  adjiistaldc       .  17(i,  177 

linishinfr,  speeds  and  feeds  for   ...  IGO 

for  cast-iron    .  181 

peneral  principles  of      175 

Pratt  i<:  Wiiitney .  .  170-181 

rowfihin<;,  non-adjvi.stahle    170,  177 

startinj;  on  the  work 186 

types  of 170 

with  drill  or  counterhore 17'J 

witli  roller  hack  rests.  Acme    100,  108 

Cleveland 75 

Pratt  cV-  Whitney IM 

Brown  &  Sharpc 

automatic  screw  machine    .S7-51 

hox  tools 47 

cam  circle  divisions 56 

cam-shaft  ilrive    .   39,  42 

cam  temi)let      .  .        54 

camming  tables    61-63 

cams,  laying  out 52-03 

capacities 51 

change-gear  system 39 

change-gear  tables     61-63 

collet  o|)eration       42 

countershaft  arrangement 51 

cros,s-slidc  cams    39,  45 

cros.s-sli(le  cams,  laying  out    56-59 

cross-slide  mechanism     44,  45 

determining  spindle  revolutions  in  camming 52-56 

die  holders 47,  49 

feed  shaft,  trij)ping  levers,  etc 45 

hollow  mills,  etc 47 

nurling  tools 48 

screw-slotting  attachment    50 

spindle  and  chucking  mechanism    38-42 

spindle  and  clutches    39,  40 

spindle  drive     39 


242  INDEX 

Brown  &  Sharpe  pages 

automatic  screw  machine  spring  collet  and  feed  chuck    40,  42,  47 

stock  feed    42 

tap  and  die  revolving  attachment 49 

turret  and  cross-slide  tools     46-49 

turret-indexing  mechanism       43,  44 

turret  slide  and  turret 43,  44 

turret-slide  cams    39,  43 

turret-slide  cams,  laying  out    56-59 

turret-tool  diagram    58 

with  constant-speed  drive 64-66 

spindle  and  clutches    ...        65 

work  deflector 46 

Burnishing  with  rolls  in  nurl  holder    233 

Bashing  box  tool    178,  179 

Button  dies 196,  200 

adjustment    201 

cutting  action     201 

cutting  edge  location 202 

hobbing  out      200 


C 

Cam  angles,  Pratt  &  Whitney,  calculations  for 15-18 

finding  graphically 18-20 

tables  of  corres{)onding  feeds     29-36 

Cam  circle  divisions,  Brown  &  Sharps   56 

drums  and  disks,  Pratt  &  Whitney      4,  5 

drums,  Pratt  &  Whitney,  development  of 13-20,  27 

layout,  Brown  &  Sharpe (insert  54) 

Pratt  &  Whitney (insert  18)      19,  27 

shaft  and  spindle  drive  diagram,  Pratt  &  Whitney     22 

shaft  drive.  Acme    97-99 

Brown  &  Sharpe 39,42 

Cleveland 69,  70 

Gridley  multiple-spindle     122 

Gridley  single-spindle    80 

Potter  &  Johnston     136 

Pratt  &  Whitney 8,  22 

Prentice     148 

Universal 116,  117 

templet,  Brown  ct  Sharpe 54 

Cams  and  tools,  Potter  &  Johnston,  record  of 142,  143 

Brown  &  Sharpe,  index  for  laying  out   54 

laying  out     52-63 

chuck-operating.  Acme 100 

Brown  &  Sharpe 42 

Cleveland   71 

Gridley  multiple-spindle    122 

Gridley  single-spindle     78 

Pratt  &  Whitney 12-14 

angles  of     12 


l.NDLX  243 

PAGES 

Cams,  chuck-opcrating,  I'liivcrsjtl   114 

cross-slide,  Acme      99 

Brown  it  Sliarpe  .19,  45 

laying;  out .  .  :,ry-M 

Clcvclaiul G'J,  70 

(!ri<llcy ....        82 

Potter  A:  Joliii.stoii     137,  i;iS 

Pratt  &  Whitney 13, 20, 2«i,  27 

layout    13,27 

feed-refrulatinji,  Clevelaml    G9,  70 

forminjr  ami  ciit-olT,  Pratt  iV;  Whitney     .  4,  13,  -JO,  2«),  27 

indexing,  Pratt  it  Whitney,  aiifiles  of  .  .  ].'> 

Pratt  it  Whitney,  <reneral  arraufrenient  nt  4,  13 

makinj:  and  attaehiiiji    .  .  .  20,  28 

stock-feed.  Brown  it  Sharpf  42 

Cleveland  ...  71 

Pratt  it  Whitney,  ande.s  of    .  .12 

tool-slide.  Acme .99,  103 

Cridley  nuiltiple-s|)in(lle      122,  123 

turret-slide,  Brown  it  Shari)e 39,  43 

layiiiii  out  ,   5()-.")9 

Cleveland      .  .  .  .  .09, 70 

CIridley  single-spindle .  .  ,78-80 

Potter  «t  Johnston    ...      137 

Pratt  &  Whitney,  angles  of  ....  17-20 

layout  of  13-20,27 

Camming  diagram,  Clevelaml    .  .        70 

Brown  it  Sliarj)e  automatic,  determining  spindle  revoIution.s      52,  56 

tai)le.s  for     . 61-63 

Pratt  it  Wiiitney  automatic 12-36 

tables  for     .  29-36 

Chamfering  and  drilling  tool,  coml)ination,  Cleveland  75 

Change-gear  system.  Acme   97 

for  threading  spindle     .  104 

Brown  it  Sharpe    39 

Potter  it  Johnston     136 

Universid .  .      116 

Change-gear  tables,  Brown  it  Sharpe     01-03 

Chasers  for  dies,  in.serted 200 

Chips,  clinging  to  screw  machine  tools     234-238 

trouble  due  to  heating .  .     234 

welding  action 234,  238 

Chuck  and  face  plate.   Prentice 149 

mechanism,  Acme 100,  101 

Alfred  Herlx'rt  magazine    129 

Brown  it  Sharpe  40,  42 

Cleveland 69 

Cridley  multiple-spindle     122 

Gridley  single-spimlic    7S,  79 

Pratt  &  Whitnev  5 


244  INDEX 

PAGES 

Chucks,  spring  (see  Collets) 

Circular  and  dovetail  forming  tools 210-229 

applications  to  work 225-228 

Circular  cut-off  tools,  clearance  of 234 

forming  tools,  arrangement  in  pairs 229 

clearance  of 210,  212,  234,  235 

diameters  of 212 

diagrams  for  finding    213-216 

finding  at  different  points 212-217 

finding  true  cutting  depth    213,  217 

finishing  in  lathe 213 

finishing  with  master  tools     217-219 

finishing  with  transfer  method 217,  218 

location  off-center    211-213 

master  tool  fixture 218 

master  tool  templet     218,  219 

methods  of  making    213,  221 

positions    226,  229 

post  for,  adjustable 222 

post  for,  Pratt  &  Whitney 221-228 

post  for  two  tools 223 

testing    221 

Clamp  collars  for  hollow  mills      182 

for  spring  dies 196 

Clearance  for  box  tool  back  rests 179 

for  counterbores   191 

for  drills 189,  238 

for  internal  cutting  tools      235-237 

side  and  front,  for  circular  forming  and  cut-off  tools 234,  235 

Cleveland  automatic 

turret  machine    67-77 

adjustable  boring  tool    75,  76 

arrangement  of  cams    69,  70 

box  tool  with  roller  rests     75 

cam-shaft  drive     69,  70 

camming  diagram     70 

capacities 76 

chuck-operating  cams     71 

combination  drilling  and  chamfering  tool 75 

combination  forming  and  cut-off  tool 76,  77 

countershaft  arrangement     70 

cross-slide  cams     71 

die  and  tap  holder    75,  76 

feed-regulating  cams      70 

general  system  of  operation    69 

independent  cut-off  attachment     73 

roller  steady  rest 75,  77 

setting  up  chart       72 

speed  and  feed  regulation    73 

spindle  drive    67 

stock-feed  cam 71 


IMJKX  245 

Clevolaiul  automatic 

turret  machine  pages 

third  .si)iii(lle-speo(l  attachment    74 

turret  and  cross  sUch-s    69 

turret  tools 74-77 

varial)le  feed  mechanism      71 

with  iiiaj^azine  feeil 126,  127 

("levelaiid  doulile-spiiidle  phiin  automatic  machine    9.'i,  94 

work  done  on 94 

Collets  and  feed  ciiucks,  Acme 83,  107 

Brown  &  Sharpe     47 

spriiiK    171-174 

Collets,  spring,  fixture  for  firindinfi     I7',i,  174 

hardeniiifi     172-174 

interior  form    172 

l)reventinp;  distortion 172-174 

relieving  nose 174 

slitting    172 

taper  arhor  for  turning    173 

turning  in  lathe 171 

Counterhores  and  drills,  flat      190 

holder  for 190 

clearance 191.  235 

speeds  and  feeds  for 1 70 

stei)ped I'M),    I'.d 

Cross-<lrilling  attadunent.  Acme Ill 

Cross-slide  mechanism,  Acme 106 

Brown  ct  Sharpe     44,  45 

Clevelaiul 69 

CIridley 82 

Potter  it  Johnston    138 

Pratt  ct  Wliitney 7 

I'niversjil    118 

Cut-off  tools,  clearance  of     234 

Cutters,  box  tool  (s«^>e  Box  Tool  Cutters) 

forming  (see  Forming  Tools,  also  Circular  and  Dovetail  Tools) 

Cylinder  revolving  and  locking  mechanism,  Acme     100,  101 

Gridley 124 

D 

Deflector,  Brown  it  Sharpe 46 

Die  and  tap  holders,  Acme       .  106.  lOS 

Brown  it  Sluupi'  47.  49 

Cleveland 75.  76 

Prentice    150 

Die  and  tap  revolving  attachment,  Brown  it  Sharpe 49 

head,  Alfre.l  Herbert    90 

hohler,  Cridley    85,  86 

Pratt  it  Whitney 208 

liolders 207 

Dies  and  taps,  sizing 206 

testing  threading  action '-06 


246  INDEX 

PAGES 

Dies  and  taps,  types  of 195 

beveling  work  before  running  on 202 

Dies,  button    196 

adjustment  of    201 

cutting  action      201 

cutting  edge  location   202 

bobbing  out     200 

inserted  chaser,  Pratt  &  Whitney 196 

inserted  chasers  for    200 

speeds  for    169 

Dies,  spring 196,  197 

cause  of  chattering  199 

clamp  collars  for     196 

cutting  edges   199 

hardening     198 

hob  taps  for     198 

internal  form   197 

number  of  prongs 197 

table  of  dimensions 206 

tapping  out    198 

Double-spindle  plain  automatic  machine,  Cleveland    93,  94 

work  done  on    94 

Double-turret  screw  machine,  Spencer   91,  92 

work  done  on    92 

Dovetail  forming  tools,  clearance  angle    213 

clearance  of 210-212 

finding  true  cutting  depth     213,  217 

finishing  with  master  tool   219,  220 

methods  of  making 213-221 

pair  with  proper  clearance    228 

planing 213 

posts  for  223-225 

setting  planing  tool  with  micrometer  and  size  blocks  ....      219 

templet  for 219,  220 

Drill  and  guide,  Gridley 83 

holders.  Acme    106,  108 

Alfred  Herbert 90 

relief 237 

Drills  and  counterbores,  flat    190 

form  of  flute 237,  238 

clearance  of 189 

counterbores  and  other  internal  cutting  tools 187-194 

serrated,  stepped,  and  fluted  lips 188,  189 

single-lip    188,  189 

starting    187,  188 

twist  and  straight  flute     188 

Drilling  and  chamfering  tool,  combination,  Cleveland     75 

attachment,  cross.  Acme Ill 

speeds  and  feeds  for 168 

Drive  for  cam  shaft  (see  Cam  Shaft  Drive) 
for  spindle  (see  Spindle  Drive) 


INDEX  247 

E 

PAGES 

Eccoiitrio  turiiiiif;  mechanism,  CJridloy  semi-automatic  piston  ring  machine   14.5 

End-inilliiif;  attachment,  Acme    112 

nuHinfj     2'.^ 


Kaciiifr  liar,  hack,  Potter  ^-  .Johnston .  .      1.37 

tools    187,  188 

P'eed  and  speed  reguhition,  Cleveland 7.3 

cams  for  main  tool  slide,  Acme    102,  10.3 

for  stock,  Acme 100 

Brown  cV:  Sharpe 42 

("levehmd 71 

Pratt  iV:  Whitney,  angles  of .  .        12 

for  turret,  Pratt  it  Wliitney,  finding  angles  of    17-20 

change  mechanism,  Gridley  multiple-spindle 122,  123 

chucks,  hardening 174 

driving  mechanism,  Acme 97,  98 

Brown  «t  Sharpe 39,  42 

Cleveland 71 

(iridley  multiple-spindle      122,  123 

Cridley  single-spindle    80,  81 

Potter  A:  Johnston     .  .      136 

Pratt  &  Whitney s,  9,  10,  21 

Universal     .  1 16,  117 

Prentice     148 

magazine.  Cleveland 126,  127 

regulating  cams,  Cleveland      .        70 

shaft,  tripping  levers,  etc..  Brown  &  Sharpe .        4.3 

variation.  Potter  it  Johnston 136 

Feetis  for  screw  madiine  tools  (see  .Speeds  and  Feeds) 

with  (litTerent  cam  angles,  Pratt  it  Whitney,  tables  of 29-36 

Finishing  box  tool,  adjustable 17ti,    177 

Fixture  for  grinding  spring  collets 173.  174 

Flat  drills  and  counterbores 190 

reamers    192 

Forming  cams  (see  Cams,  Cross  Slide) 

long  work,  method  of  supjwrting    227 

short  screw  ami  other  work    227 

speeds  and  feeds  for 167 

Forming  tool  positions    226,  229 

posts,  adjustable    225 

posts  for  straight  tools    224 

for  two  circular  tools 223 

Pratt  &  Whitney   221-225 

Forming  tools  and  methods  of  making  them 210-229 

and  their  clearances   21 1-213 

applications  to  work     225-228 

circular,  diagrams  for  finding  diameters     213-216 

diameters     212 


248  INDEX 

PAGES 

Forming  tools,  circular,  finding  diameters  at  different  points 212-217 

finding  true  cutting  depth 213,  217 

finishing  in  lathe     213 

finishing  with  master  tools    217,  219 

finishing  with  transfer  method   217,  218 

location  off-center 211-213 

master  tool  fixture    218 

master  tool  templet    218-220 

testing 221 

clearances  of    210-212,  234,  235 

dovetail,  finishing  with  master  tool 219, 220 

pair  with  proper  clearance   228 

planing 213 

setting  planer  tool  with  micrometer  and  size  blocks 219 

finding  true  cutting  depth    213,  217 

methods  of  making    213-221 

types  of , 210 

G 

Gears,  change  (see  Change  Gear  System) 

planetary  for  Pratt  &  Whitney  feed-drive  mechanism    8,  9 

Gridley  midtiple-spindle 

automatic  turret  lathe 119-125 

capacity 125 

indexing  mechanism    124 

feed-change  mechanism 123 

feed-driving  mechanism    122,  123 

spindle  drive 121,  122 

threading  mechanism    123 

tool  slide    120-123 

tool-slide  cams    122,  123 

Gridley  semi-automatic 

piston  ring  machine     144-146 

boring,  turning  and  cutting-off  tools     145 

eccentric  turning  mechanism    145 

piston  ring  casting    145 

Gridley  single-spindle 

automatic  turret  lathe 78-88 

cam-shaft  drive    80 

capacity 78 

countershaft  arrangement 87 

cro.ss-slide  mechanism   82 

die  holder    85,  86 

finishing  slide,  12-inch 84 

spindle  and  chucking  mechanism    78,  79 

spring  collet  and  feed  chuck 78,  79 

turret-indexing  mechanism 80,  81 

turret  slide  and  turret 78-80 

with  motor-drive  and  control 86-88 

Grinding  fixture  for  spring  collets        174 


INDEX  249 

H 

PAGES 

HandliriK  material  in  screw  machine  department 160 

Hardeninj;  spriiifi  collets  and  feed  chucks    172,  174 

sprinfi  (lies 198 

Holders,  die  (see  Die  Holders) 

drill  and  counterbore 191 

reamer,  floating    192 

Hollow-mill  damp  collars 182 

ilimensions 182 

tooth  position 183 

Hollow  mills,  Brown  &  Sharpe 47 

spcetls  antl  feeds  for 162,  165 


I 

Iiitlepeiident  cut-ofT  attachment,  Cleveland 7'.i 

Index  for  lajnng  out  Brown  &  Sharpe  cams    54 

Indexing  cams,  Pratt  &  Whitney  turret,  anjiles  of 15 

mechanism  (see  Turret  Revolving  and  Locking  Mechanism) 

Inserted  chaser  die,  Pratt  it  Whitney 196 

chasers  for  dies 200 


J 

Jaws,  spring-chuck,  methotls  of  hardening 172 

slitting    172 

relieving  on  hearing  surface    174 

L 

Laying  out  Brown  it  Sharpe  cams    52-63 

index  for 54 

tallies  for    61-63 

typical  layout (insert )       54 

Laying  out  Pratt  it  \\'hitney  cams  12-36 

tables  for     29-36 

typical  layouts (insert  18)     13,  27 

Locking  bolt  mechanism  (see  Turret  Revolving  and  Locking  Mechanism) 

Lubrication  of  work  and  tools 236 


M 

Machine  reamers  and  holders     191,  192 

Magazine  attachment,  Cleveland 126,  127 

tools  for  finishing  pistons 127 

Magazine  automatic,  Alfre<l  Herliert 128-134 

carrier  mechanism 130 

feed  for  shells 130 

tools  for  finishing  shells  on 133 

Master  tools  for  finishing  circular  forming  tools    217-219 

fixture  for    217,218 


250  INDEX 

PAGES 

Master  tools  for  finishing  dovetail  forming  tools 219,  220 

Material,  handling  in  the  screw  machine  department    160 

Mining  attachments.  Acme Ill,  112 

Models  for  use  in  setting  screw  machine  tools   161 

Motor  drive  and  control,  Gridley 86-88 

Multiple-spindle  automatic  screw  machine.  Acme     95-113 

Gridley 119-125 

Prentice    147-155 

Universal    114-118 


N 

Nurling,  end,  and  burnishing   233 

tools.  Acme    109 

and  their  applications     230-233 

Brown  &  Sharpo 48 

holders  for 231 

metliods  of  applying    230-232 

operation  of 230 

types  of 231 

O 

Operation  and  tool  position  chart,  Cleveland    72 

Potter  &  Johnston    142,  143 

Operator's  duties    159 

P 

Piston  ring  machine,  Gridley  semi-automatic 144-146 

Points  in  setting  up  and  operating  automatic  screw  machines 159-161 

Posts  for  forming^  tools    221-225 

Potter  &  Johnston  automatic 

chucking  and  turning  machine 135-143 

back-facing  bar 137 

cam-shaft  drive    136 

capacities 140 

change-gear  system 136 

cross-slide  mechanism   137,  138 

feed  variation   136 

spindle  drive     135,  136 

tool  position  record 142,  143 

turret  and  cross-slide  tools     138-140 

turret-slide  cams    137 

Pratt  &  Whitney 

automatic  screw  machine 3-11 

angles  for  chucking  cams    12 

for  indexing  cams 15 

for  stock-feed  cams    12 

for  turret-feed  cams 17-20 

box  tools 176-181 


JM)i:x  251 

J'nilt   .V:  Wliitncy 

aiitomatif  screw  iiiachiiiL'  p\ge.s 

Im).\  tools  Willi  roller  rests 181 

cam-ansle  c-oinpiitations     15-18 

aiijiles,  fiiuliiifi  Krapliicaily    18-20 

t:il)les  of  corresi>oii(linfj  fowls    29-.'10 

arraii'reiiient     4   I'.i 

ilruiiis  and  disks -J,  5,  l.'l 

(Iruiiis,  (levelo|)iiieiit  of l.i-JO,  27 

'ayoiit (insert,  18)     i;i  ]<),  27 

roll  sj)aces Ki,  17_20 

shaft  ami  spindle  drive  iliagram    22 

shaft  drive     8  22 

cainmiii<i  of     12-36 

of  chuekini:  driiiii    12-14 

of  cross-slide  disk 13,  20,  27 

of  tiirret-sliile  drum  13-2S 

tables    29-36 

cajiacities j  1 

countershaft    s.  1(1,  L'J 

cross-slide  mechanism  7 

cutting-offcanis .4,  13.  20,  26,  27 

die  holder    •_>()7 

die  with  inserted  chasers  KHi 

feed  calculations  for 1.) 

drivinsi  mechanism S.  <),  lo,  jl 

j)ulley  diameters  .  21-24 

tables  for     29-36 

formitifi  cams    4,  i;j,  40,  26,  27 

tool  posts    221   22o 

indexing:  mechanism  for  turret     6 

nijikinp:  and  attaching  cams       26,  28 

pulley  sizes  and  speed  and  feeil  tables 33-36 

spindle  and  chucking  mechanism   4,  5 

<inve 4.  10.21.22 

drum  and  feed-j)ulley  ratios 21 -2o 

sprinji  collet  and  feed  chuck     4,   5 

taper-turninfj  tool    183 

turret-indexiiiff  mechanism    6 

slide  and  turret (i 

slide  cannninj; 13-28 

two-speetl  sjjindle  dri\e 2.5 

cam  computations  for  .  .  .        2.") 

cam  layout  for    26,  27 

Prentice  multiple-spindle 

automatic  turret  machine     147-1.").3 

cam-shaft  drive    148 

capacities 1.5;j_  1.5.3 

chuck  and  face  plate   149 

countershaft  arrangements 1.53 

<louble  head I.54 

spindle  drive     ...  14S 


252  INDEX 

Prentice  multiple-spindle 

automatic  turret  machine  pages 

threading  mechanism    148 

tools  for 150-152 


R 

Rake  and  clearance  of  tools 236,  237 

of  cut-off  tools,  positive  and  negative,  effect  of 236 

Reamers  and  holders,  machine 191,  192 

flat    192 

machine,  clearance  for 191 

number  of  flutes  in 193 

rose 191 

taper      193 

three-flute 192 

Reaming,  speeds  and  feeds  for     169 

Recessing  tools 193 

Record  of  tool  positions,  Cleveland 72 

Potter  &  Johnston     142,  143 

Rests,  box  tool  (see  Box  Tool  Rests) 

Roughing  box  tool,  non-adjustable     176,  177 

S 

Screw  machine  taps  and  dies      195-209 

slotting  attachment.  Brown  &  8harpe 50 

Acme 113 

threading  dies 195-202 

Setting  up  and  operating  automatic  screw  machines     159 

Setting  up  models 161 

chart,  Cleveland     72 

'  Potter  ct  Johnston     142,  143 

Shaving  tools.  Acme    107-110 

Side-milling  attachment.  Acme    112 

Sizing  dies  and  taps     206 

Slotting  and  milling  attachments.  Acme    111-113 

Speeds  and  feeds  for  drilling 168 

for  finish  box  tool    166 

for  forming    167 

for  hollow  mills 162,  165 

for  reaming  169 

for  screw  machine  work    162-170 

for  turning  brass    162,  164 

for  turning  screw  stock     162,  163 

Speeds  for  dies    169 

Spencer  double-turret 

automatic  screw  machine    91,  92 

cam-shaft  mechanism,  etc 91 

work  done  on    92 

''  Spindle  and  chucking  mechanism.  Acme    100,  101 

Alfred  Herbert  magazine    129 


INDEX  253 

PACKS 

S|iiiiillc  ami  chucking  mechanism,  Brown  &  Sharpe 38-42 

Clovchind 67-69 

(iridley,  multiple-spindle    122 

(Iriilicy,  single-spindle     78,  79 

Pratt  iV:  Wliitiiey 4,  5 

Spindle  and  clutches,  Brown  A  SliarjM'  automatic  with  constant-speed  drive     .  .  .       65 

and  feed-drive  ratios,  Pratt  A:  Whitney 21-25 

Spindle  drive,  Acme 97 

Brown  ct  Sharpe    39-40 

constant-s|)eed    65 

Cleveland 67 

Gridley  multiple-spindle  121 ,  122 

Gridley  sinple-spindle    78 

Potter  A:  Johnston     135,  136 

Pratt  iV:  Whitney 4,  10,  21,  22 

Prentice     148 

I'niversid     114- 116 

Spindle  revolutions,  determininfi;  in  canuniuK  Bniwti  tV:  Sharix'  iiiacliiiM'     52-56 

speeds,  Brown  &  Sharpe,  tables  of .  .  .  .  .  .61-63 

Pratt  ct  Whitney,  tables  of 33-36 

Spotting:  and  facing  tools    187,  188 

Spring  collets  and  feed  chucks     171-174 

(Also  see  Collets) 
Spring  dies  (see  Dies,  Spring) 
Starting  drills    187,  188 


Table  of  allowances  in  sizing  work  for  threatling 205 

of  spring  die  dimensions   206 

of  tap  sizes  and  lands    204 

Tables  for  finding  feed  pulley  diameters,  on  Pratt  A:  Whitney  automatic    29-32 

for  use  in  cannning  Brown  «.t  Sharpe  automatic 61-63 

of  feeds  for  ditTerent  cam  angles  on  Pratt  tV  Whitney  automatic    29-36 

of  specfls  and  feeds  for  screw  machine  work     1()2   170 

Tap  and  die  holders.  Acme 106,  108 

Brown  &  Sharpe 47-49 

Cleveland 75,  76 

Pratt  ct  Whitney 208 

Prentice     150 

revolving  attachment.  Brown  &  Sharpe 49 

Tap  relief     205 

spiral  flute 205 

Tapping  out  spring  dies .198 

Taps  and  dies,  screw  machine    195-209 

sizing    206 

testing  threading  action    206 

cutting  edges  for  brass,  copper,  etc 203 

Echols"  patent     203.  204 

length  and  luunber  of  lands     204 

TajM'r  reamers  .      193 


254  INDEX 

PAGES 

Taper  turning  tool,  Brown  &  Sharpe 46,  48 

Gridley 85 

Pratt  &  Whitney 183 

Templet  for  cams,  Brown  &  Sharpe    54 

for  forming  tools 218-220 

Testing  circular  forming  tools    221 

Third  spindle-speed  attachment,  Cleveland     74 

Thread-rolling  tools.  Acme     109,  110 

Threading,  allowances  in  sizing  work  for 205 

dies     195-202 

mechanism,  Acme    104,  105 

Gridley 123 

Prentice     ' 148 

Universal 115 

short  work  with  dies   202 

speeds  for  taps  and  dies    169,  170 

Tool  position  record,    Cleveland    72 

Potter  &  Johnston 142,  143 

posts,  forming 221-225 

slide.  Acme 102,  103 

Gridley  78,  SO,  122,  123 

Universal 114 

Tools,  Acme 106-113 

Alfred  Herbert 90 

magazine   133 

box,  and  other  external  cutting  ai)pliances    175-180 

(Also  see  Box  Tools) 

Brown  &  Sharpe     46-49 

Cleveland   74-77 

magazine 127 

forming  (see  Forming  Tools,  and  Circular  and  Dovetail  Forming  Tools) 

internal,  for«i  of  flute    238 

Gridley  83-86 

Gridley,  piston  ring    145 

nurling  (see  Nurling  Tools) 

Potter  &  Johnston    138-140 

for  fly  wheels     140 

for  gas  engine  pistons 140 

Prentice    150-152 

for  undercutting 151 

Pratt  &  Whitney  (see  items  under  Pratt  tt  Whitney) 

recessing 192 

spotting  and  facing 187,  188 

turner  with  roller  back  rests,  Gridley 83 

Turning  and  boring  spring  collets 171 

Turret  lathes  and  machines,  automatic  (see  Automatic  Screw  Machines) 

revolving  and  locking  mechanism.  Acme 100,  101 

Brown  &  Sharpe   43,  44 

Gridley  multijile-spindle    124 

Gridley  single-spindle 80-82 

Pratt  &  Whitney 6 


lS\)i:x  255 

PAGES 

Turnt    rcvolviii;^  ;iii<l  lockiiifi;  riu'cli:iiiisMi.  I'ri-iilico  ...  J 47-149 

riiivcrsal  I  17,  IIH 

Turifl-slide  cams,  HniuM  iV  Sli;i;|ic,  layin;^  out     ...  .")(j-o!i 

Pratt  A:  W  liitiu-y,  .iiiirlcs  of    17-20 

laying  out    I.'M'O,  27 

tahlcsof  ft'c.lscorrc'.'-poiulinf^  to  {riven  angles  '2[)-'.iii 
(.M.-^o  see  Cams,  Turret  Slifje) 
Turn-t    .slide  ami  turret  (see  items  under  Hnnvri  iV:  Sliarpe,  Clevelaud,  etc  ) 

tonl  diairraiii,  Hruwn  it  Sliarpe    58 

Twi.st  drill-s,  ciearaiiee  and  reli<'f    IS'.),  2'.iH 

fi)r  .startiii<i  hul-s    I.S7,  l.SS 

U 

Undercut  forminfi  and  cut-olf  tool,  Cleveland 70,  77 

I'ni versa!  nuiltiple-s|)indle 

automatic  screw  machine  1  14  -118 

caui-slialt  lirake   110 

drive 110,  117 

capacities 118 

clian;re-pear  sy.stem  110 

spindle  drive     II  J    110 

threadinfi  mechanism    ll.> 

turret-locking  bolt     118 


N'arial lie-feed  mechanism,  Clevehuid 


W 

\\'eldin<_'  of  cliips  to  tools     234 

\Vh\-  chips  cling  to  screw  machine  tools 234-238 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 

Los  Angeles 
This  book  is  DUE  on  the  last  date  stamped  below. 


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